This is for people that I live with.
I don’t mean any lame team building exercises, but casual group activities. It could be something mundane like organizing a trip to the store together. Movie trips would also be fine as would showing something on the home projector, though I feel like there’d be more distractions and temptation at home.
Unfortunately it’s hard to really weigh in without knowing the individuals. There are alot of factors. A hypersensory person with autism would be completely different from a hyposensory person with autism. And that’s just one factor that would make a huge difference. You might have to involve them in any plans to find out what is a no-go for each of them.
But with that in mind, knowing that any one of these could be immediately shot down: Arcades, Bowling, Zoo/Aquarium, Go-Karts. For cheaper stuff; visiting a pet store, seasonal local festival/event type stuff, a group bike ride on a park trail. Stuff that really depends on personalities and interests but gonna suggest them anyway as it might not be something a normal person would think of; the type of party that highschoolers would have thrown back in their day(junk food, music, party games), a drive out to a local train crossing when a train is scheduled to cross(depending on interest level).
In my experience VR is currently much more popular among the Autistic crowd, so if you can either go to a VR arcade, or have access to a VR headset. That might be something to ask about.
But yeah, ultimately, it’s really hard to know as we’re all largely completely different. The few “commonalities” aren’t pervasive, just more likely.