Switching between Pixel 8 and Pixel 8 Pro

hello

I've had my Pixel 8 since it came out. I'm on Fi. Now I have been given an old Pixel 8 Pro.

How easy is it to switch back and forth between phones? I like the smaller phone as it fits in my pocket better, but I might like the bigger screen and better camera from time to time.

Can anyone point me in the correct direction on how to set up the "spare" phone for easy switching between the two?

thanks!