Just switched from Canon to Sony A7 R5 I use natural light most of the time But when I use flash (on or off camera) what how should I set the camera up? thanks for your help

I upgraded from the a6000 to an A7II and managed to add my already installed playmemories by going to www.sony.net/pm/ on the computer, the link still works, good luck.

I think that @Cameratose is correct. Parameters you set for Auto ISO are only available in regular modes. Full Auto sets everything for you. That's why it's called Full Auto. I don't think I have ever used a Full Auto setting on any camera I have ever owned because you don't have any control at all.