face ID not available after replacing my screen

If anyone other than Apple or an actual Apple Authorized Service Provider, replaced the screen, they don't have access to authentic Apple parts, so if this is what you did, Face ID likely will not work on your iPhone. 3rd Party shops don't have the parts, nor the ability to reprogram what is required for Face ID. And Apple can refuse service on your phone if anyone else touched it.

Have you had it replaced at apple or an authorized service provider? If the answer to that question is yes, go back to the place where the service was provided to ask them about this

If you had it replaced by a non authorized service provider it could be that there are non-original parts used, and that is the reason you cannot use Face ID

Then Face ID will never work on your iPhone. And we aren't Apple. We're users like you. You unfortunately chose to put an unauthentic part in your iPhone and you'll just have to live with the consequence, I'm afraid.