There are lots of different wheelchairs that purport to be “all terrain”, which seems to mean anything that is designed for more challenging situations than smooth sidewalks with curb cuts. YouTube has videos showing a wide variety of them.
They range from simple, inexpensive, easy-to-maintain wheelchairs designed for rural people in developing countries to very expensive, automated gizmos for the higher end client. Some are designed for snow, sand, even climbing stairs. They’re fun to watch. Here are a few links to get you started, then check out the other ones on YouTube.