It's done in the long range FPV community. Not super common - it's expensive, and you aren't allowed to fly farther than you can see the drone (and safely fly it by sight alone, and monitor the airspace around it) but it's done.
I've not specifically kept up with the long range community, but I want to say I've recently seen videos of test flights out to 100km using an independent radio link (i.e., 5.8GHz analog video + 9xx MHz control link).
That said, power density is going to be your first limiting factor. You're either going to have to seriously tune your airframe for long-range flight (and greatly compromise performance), or you're going to have to move to a fixed-wing design.
Multirotors must maintain thrust (and therefore, expend power) to provide lift; fixed-wing designs provide lift as long as they are moving forward. The flight time of a fixed-wing design that's light enough and has a long enough glide profile is unlimited in practice. You can catch thermals and updrafts to gain speed, altitude, or both.
I have a 1m foam glider that I've flown for well over an hour. The vast majority of that time was with the motor turned completely off and the prop folded flat against the fuselage. I'd soar out over the field where I was flying. There was a creek at the edge of the field and a small hill on the other side of it, creating a "barrel" of air. Flying in low, I'd catch the bottom of that current, ride it up the hill side, then pick up speed as I crested the hill and gently turned back toward the field. That particular location is great on chilly spring and fall mornings, because the temperature gradient between the creek and wind coming over the hillside is so great.