I would think it would really depend on the disability, right? Even though I have no physical disabilities, I cannot use all the equipment in our gym. Some are more for the heavy bodybuilders & powerlifters. I would think a person who have to assess their physical disability and find the right equipment, which in larger gyms, there is a huge variety to choose from. Like, if you had only 1 arm, there are free weights you could use, or equipment that has the use of individual arms, like a bicep curl or tricep pushdown. The cable machine allows for both arms as well as one arm, similar for legs.
Lifetime Fitness (one of the gyms I belong to), has regular exercise balls, those domed shaped balls, bands, tubes, and a bunch of other things. It all depends upon one's creativity. I'm surprised at some of the uses of some of the things at my gym.
I think leaving plenty of room between equipment or aisles, having wheelchair access, if it's on the 2nd floor, an elevator (or a ramp in case of fire), would be the most practical things. In the shower areas, having enough room for a wheelchair and guard rails.
It would also be good to have staff on hand that knows how to deal with various people's physical disabilities to help show them exercises they can do to achieve their goals. Even when I've been injured, I've worked out other areas of my body with no real issues.