99% of 'possible range' is antenna height. Yours, and theirs. Most of the rest is intervening terrain. (Is there a hill/mountian between you and them?)
The rule of thumb for reliable communications is to take the square root of the antenna height in feet, and that's your range in miles. (add together the range due to the antenna at each end) You MAY get 1.5 to 2 times that far. Or you may not.
Your handheld is about 5 foot altitude. It's good for 2-3 miles, maybe 4-5 if there are no trees or buildings between the stations and flat ground. Maybe.
Most of the 'range' of a system will depend on the transmitter on the other end. If it's at 1000 feet, it's good for 32-64 miles. (34-69 counting your end) IF there's no hills in between.
If you're talking to the International Space Station, hey, you can talk 150 miles easy... because they're at 200+ miles altitude. They're in line of sight. Of course, they're also hearing every station trying to talk to them for 200 miles around them, which is kind of noisy...