Error message: 

Compile Error: Method does not exist or incorrect signature: account.Dr_Chrono_appointments__r.get(Integer) at line 58 column 22​

Problem:

I'm new to Apex and SOQL. I have two objects; Accounts (Master object) and Appointments (Child object) and I'm trying to write a trigger (With SOQL query) that returns the inital weight value (corresponding to the inital date) and latest weight (corresponding  to the most recent appointment) per account on custom fields inital_weight__c and latest_weight__c respectively. Both fields are built on the account (Persons account) object:

Code:

Trigger GetLatestAndInitalWeightValue on Appointments__c(after insert, after update) {
    Set<Id> accountIds = new Set<Id>();

    for (Appointments__c appt : trigger.new) {
        accountIds.add(appt.Patient__c);
    }

    //Elimnate the the accounts that don't have IDs for
    accountIds.remove(null);

    //SOQL query that returns that latest weight value 
    if (!accountIds.isEmpty()) {
        List<Account> accountsToUpdate = new List<Account>();
        for (Account account : [
            Select Id,
                (
                    Select Scheduled_time__c, weight__c
                    From Dr_Chrono_appointments__r
                    Order by Scheduled_time__c desc
                    Limit 1
                )
            From Account
            Where Id in :accountIds
        ]) {
           
            //Declare a decimal variable to store latest weight value 
            Decimal LW = NULL;
            
            // Get(0) to return the first element in the list value
            if (!account.Dr_Chrono_appointments__r.isEmpty()) {
                LW = account.Dr_Chrono_appointments__r.get(0).weight__c;
            }

            accountsToUpdate.add(new Account(
                Id = account.Id,
                Latest_weight__c = LW
            ));
            }
              //SOQL query that returns that inital weight value 
             
        for (Account account2 : [
            Select Id,
                (
                    Select Scheduled_time__c, weight__c
                    From Dr_Chrono_appointments__r
                    Order by Scheduled_time__c ASC
                    Limit 1
                )
            From Account
            Where Id in :accountIds
        ]) {
           
            //Declare a decimal variable to store inital weight value 
            Decimal IW = NULL;
            
            // Get(0) to return the first element in the list value
            if (!account.Dr_Chrono_appointments__r.isEmpty()) {
                IW = account.Dr_Chrono_appointments__r.get(0).weight__c;
            }

            accountsToUpdate.add(new Account(
                Id = account.Id,
                Inital_Weight__c = IW
            ));
                         
        }   
        
        update accountsToUpdate;
        
        }
      }