Explain for the crossplay

Hello.
There is a game on Xbox and offline characters created.
If I buy a game on PC, will my offline characters load up so that I can play them on PC as well?

This shouldn’t work since offline characters are saved locally. Maybe it’s possible to load the savegames on an usb stick and then import them to the PC. But you would have to find out for yourself.

It should work for your online characters, though.