Thanks Pinky for your kind response. Please check all the code

Apex Code::

public with sharing class MoveAttachment {
    Public string getId {get;set;}
    @AuraEnabled(cacheable=true)
    public static List<EntityDefinition> methodName(){
        List<EntityDefinition> ed = new List<EntityDefinition>([SELECT id, QualifiedApiName, Label FROM EntityDefinition where IsCustomizable = true]);
        return ed;
    }
    
    @AuraEnabled(cacheable=true)
    public static List<sobject> fetchRecord(string searchKey, string selectedLabel){
        string key = '%'+searchkey+'%';
        String queryStr='select id, Name from ' + selectedLabel+' where Name Like :  key';
        system.debug(key);
        system.debug(selectedLabel);
        List<sobject> recorddetails = Database.query(queryStr);
        system.debug(recorddetails);
        return recorddetails;
    }
    
    @AuraEnabled(cacheable=true)
    public static List<Attachment> getAttachment(string parentId){
        List<Attachment> attachmentDetails = [select id, name from Attachment where parentId =: parentId];
        return attachmentDetails;
    }
    
    
}




Html Code :


<template>
    <lightning-card title="Source Object" icon-name="custom:custom67">
    <template  if:true={options}>
    <lightning-combobox
            name="List of Object"
            label="List of Object"
            placeholder="Select Object"
            options = {options}
            onchange={handleChange} >
        </lightning-combobox>
    <p>Selected value is: {selectedLabel}</p>
</template>
</lightning-card>
<lightning-card title="Record Details" icon-name="custom:custom63">
    <div class="slds-m-around_medium">
        <lightning-input type="search" onchange={handleKeyChange} class="slds-m-bottom_small" label="Search" value={searchKey}></lightning-input>
        <template if:true={recorddetails.data}>
            <template for:each={recorddetails.data} for:item="datas">
                <p key={datas.Id}>{datas.Name}</p>
            </template>
        </template>
        <lightning-button variant="success" label="Show Attachment" title="Successful action" onclick={optionss} class="slds-m-left_x-small"></lightning-button>
    </div>
</lightning-card>
<lightning-card title="Attachments" icon-name="custom:custom100">
    <div class="slds-m-around medium">
            <lightning-checkbox-group name="Checkbox Group"
                                      label="List of Attachment"
                                      options={attachmentDetails.data}
                                      value={values}
                                      onchange={handleChanges}></lightning-checkbox-group>
    </div>
</lightning-card>
</template>



Javascript code : commented included too

import { LightningElement, wire, track } from 'lwc'; 
import methodName from '@salesforce/apex/MoveAttachment.methodName';
import fetchRecord from '@salesforce/apex/MoveAttachment.fetchRecord';
import getAttachment from '@salesforce/apex/MoveAttachment.getAttachment';


export default class attachmentMove extends LightningElement {
    record= [];
    records= [];
    recordss=[];
    resultss=[];
    result= [];
    results= [];
    error= [];
    data = [];
    errors= [];
    datas = [];
    errorss= [];
    datass = [];
    dataa = [];
    eror;
    datasss =[]
    @track parentId=[];
    @track searchKey;
    @track selectedLabel;
    @track parameterObject;
    @track recordId;
    @wire(methodName)
    wiredsobjectName({error, data}){
        if(data){
            if(data.length>0){
                for(let i=0;i<data.length;i++)
            {
                this.record.push ({label: data[i].Label, value: data[i].QualifiedApiName });
                console.log('check=====>', this.record[i]);
            }
        }
            this.result = this.record;
        } else if (error){
            this.error = error;
            this.result = undefined;
        }
    }
    get options() {
        console.log('option',this.result);
        return this.result;
    }
    
    handleChange(event) {
        this.selectedLabel = event.detail.value;
    }
    
    @wire(fetchRecord, {searchKey:'$searchKey', selectedLabel:'$selectedLabel'})recorddetails;
    @wire(getAttachment, {parentId:'$parentId'})attachmentDetails;
    get parentIds(){
        this.parentId = this.recorddetails.data.id;
        console.log('parentId---->', this.parentId);
        return this.recorddetails.data.Id;
    }

    get optionss(){
        return this.attachmentDetails.data;
    }
    get values(){
        return this.attachmentDetails.data;
    }
    get selectedValues(){
        return this.values.join(',');
    }

    handleChanges(e){
        this.value = e.detail.value;
        
    }

    handleKeyChange(event) {
        const searchKey = event.target.value;//this.template.querySelector('lightning-input').value;
        this.searchKey = searchKey;
        //this.parentId.push({key : this.recorddetails.Id});
        this.parentId = this.recorddetails.data;
        
        console.log('this.parentId---->', this.parentId);
        return this.recorddetails;
    }

}

/*
@wire(fetchRecord)
    wiredRecordDetails({errors, datas}){
        if(datas){
            if(datas.length>0){
                for(let i=0;i<datas.length;i++)
            {
                this.records.push ({label: datas[i].Name, value: datas[i].Id });
                console.log('check record=====>', this.records[i]);
                this.parentId = datas[i].Id;
                console.log('this.parentId---->', this.parentId);
            }
        }
            this.results = this.records;
        } else if (errors){
            this.errors = errors;
            this.results = undefined;
        }
    }
    @wire(getAttachment)
    wiredAttachmentDetails({errorss, datass}){
        if(datass){
            if(datass.length>0){
                for(let i=0;i<datass.length;i++)
            {
                this.recordss.push ({label: datass[i].Name, value: datass[i].Id });
                console.log('check attachment=====>', this.recordss[i]);
                this.parentId = datass[i].Id;
                console.log('parentId---->',this.parentId[0]);
            }
        }
            this.resultss = this.recordss;
        } else if (errorss){
            this.errorss = errorss;
            this.resultss = undefined;
        }
    }
    */




Actually it's providing value for recorddetails properly on html but I need to pass the recorddetails.Id value to the parentId so that i can retrieve related attachment.