ESim on a 2020 SE

I read a post of an Iphone 11 user about two lines and "turning off" one when not in use. I have an unlocked 2020 SE with a European number. I will add my US number with an eSim. I want to turn off the European number while in the US and the same for the US phone while overseas as neither has an international plan. Is this possible on the SE? Further, can I use the "overseas" number (whether US or EU) on wifi to check imessage/whats app/etc. while on the regional plan of the number I am using? Hope that is clear. Thanks for any help here.