From my understanding, the service area of paratransit is described as:
transit systems that run fixed routes must also provide ADA complementary paratransit service within ¾ mile on either side of the fixed route; this is considered to be the maximum distance a rider would travel to reach a bus or train stop.
basically what local public transit is +¾ mile.
So, while you have permission to use a neighboring state’s paratransit, you would need to find your own way to that region / state via long distance bus or plane. There is a post here about traveling on the greyhound bus in a wheelchair. So, you could take paratransit to the bus stop (or airport), take that to the region / state you want to visit, and take paratransit in that city to your hotel etc.