Only thing I have come up with is to put the subject detection on my custom menu. Makes it much faster, but not single button. You could also set two adjacent C modes on the dial to the same settings but one with people, other with animals.
I just went through this a few days ago. My R6II has that option and I wish my R7 did. As stated you can use modes 1-3. I assigned mine to the Green menus as I try to keep both cameras as consistent as possible.
Look for this icon when mapping. Not sure the R6 has it.
