The closest that you can do in your use case would be to duplicate your base and choose the option “Create an empty base”. It will keep all your fields, minus the records. I don’t know if this is what you are looking for, but this is the closet that you can get. Unless, if someone else in the Community has some suggestions.
In terms of wanting to create a different template in a record, Airtable formats all fields in a longitude format. So, what change you make in one field, it will affect all the records.
I guess, one way to create different templates is to create separate tables. This way you can have each table setup the way you need to.
You could name one table YouTube and the other Instagram and then set up your fields accordingly. If you need to link any of the fields, or use any other function, i.e. Lookups, Rollups, etc., you can also do that quite easily.