The Black Book: A Christmas Story

A whole family gets portaled to a fantasy world with light LitRPG elements just before Christmas. They get to choose their fantasy race, class, and talent when they arrive and the main character, a transgirl, is able to magically change to being biologically female as well. The family gets settled in, there's almost no conflict, and it's just a pleasant wish fulfilling time.

About halfway through there's some God and Jesus talk, which took me by surprise. The “A Christmas Story” should have been a hint but it's such a non-secular holiday in my experience that I forgot.