If yes, I would need some help or document regarding this. Thanks in advance.

I have a requirement where I need to send sample requests to Contact or Lead which is achieved with a 'Sample Request' custom object with look up relationship to 'Contact' as well as 'Lead'. There will a 'Sample Request' button in the Contact Page and also one on the Lead Page. When user clicks on Sample Request from Contact, I should show only Contact look up whereas when it comes from Lead, it should show only the Lead look up. I had to create 2 page layouts to accomplish this and assign unique record types  for the 'Sample Request' custom object.

I am wondering if this can be achieved similar to how 'Name' field works in 'Task' UI. In 'Task' standard object there is field called name which is of datatype ' Lookup(Contact,Lead)  ' This provides a UI which  contains  a dropdown with 'Lead' or 'Contact' values together with a text field and a lookup icon.

Doing some research I do not think this is a standard feature available.

If this can be done, I need only one page layout.

Any suggestions