The Maxxis 2.5" WT tires are as about as wide as I would want to go, also IMO the sweet spot for wide tires.Trek full stache can run 29x3" tires, but that's likely it.
There are probably quite a few that can do 650bx3" "plus bike" tires if that's your fix.
Most standard tires are now 2.5 or 2.6 which is really pretty fat.
I do run a 2.6" on the back of my hardtail because hardtail.