I have a 13 month cat, a domestic short hair brown tab. I've seen people equip cats with wheels these days like hamsters but that seems to be mainly bengals with much more energy and need to exercise. I spend the bulk of my day at work and my cat has a small toy, and the hurricane frisbee ball toy. At night before bed I try to laser pointer it for 5-10 mins and I get a few sprints out of it. I'm not sure if this is enough though?
The activity level of cats varies widely. Some breeds are known for being extremely active, e.g. Bengals, but it also depends on the particular cat and their environment.
As @Beo commented, the key is to look for signs they're not being stimulated enough. This could be bringing you toys, running back and forth, playing with invisible toys, nipping or pawing at you like they would another cat, or anything else that may indicate they want more attention from you. Note that, to a cat, negative attention is still attention, so this can include deliberately misbehaving.
Generally, if you have two cats that get along, they will keep each other plenty busy. If two days don't get along, though, it's often because one has a higher energy level and the other is annoyed by it; playing with that cat to burn off some of its energy may help them get along better.
Finally, be aware that cats are evolved to have brief periods of activity separated by long periods of light sleep, up to 20 hours a day in total. So, just sleeping a lot (by human standards) doesn't mean they do or don't get enough activity; you have to examine the periods when they are actually awake.