It’s been a long time since I played PS2, but the analog triggers and bumpers and X/O/Tri/Sq got a fair amount of function. Ace Combat is of course a racing/flying category, but a non-racing function was Square pressure zoomed out the map variable. The other 3 shape buttons didn’t utilize pressure sensitivity, but the triggers and bumpers variable controlled throttle/brake and yaw.

I vaguely remember an FPS game where aiming down sights with binoculars equipped offered variable zoom.

But realistically, there’s a ton of uses for variable buttons, but devs have to employ them. I’d bet the utilization of the 6 extra PS buttons is nonexistent for any cross-platform games, especially PvP games. If you stick to PS-only titles, you’d probably find more examples. Unfortunately, I stopped at PS2, and nearly everything in my collection was racing. I can’t remember the details, but something about the Xbox one controller was lacking when I played the Spyro trilogy re-release/re-port.