Combining fields

I’d like to combine some fields and display them in the form before submitting.
An example could be a first name and last name text field (2 fields) and a domain drop down list.
I would like a 4th field to show / save
Note that I’d also need to add the extra text like the . (dot) between first and last and the @
I have been searching the forums but I haven’t seen an entry that matches this so I’m not sure it is possible.
Thanks for any guidance.

The use case described can’t be done using Gravity Forms out of the box. Maybe the following third-party add-on created by one of our certified developers could help: Gravity Forms Populate Anything - Gravity Wiz

Make sure to confirm with the author if it could fit your needs before a potential purchase: Have a question about Gravity Perks? - Gravity Wiz

Thanks for the reply.
I’ll have a look