FPV used in combat these days go a lot further than 4km, you can punch out to 25km+ with a good repeater setup easily, 10-15km with a good mast setup, and strikes using FPV quads out to 45km have been documented (but these are rare).

You just need to plan your battery selection and consider the electronic warfare environment to go the distance.

There’s also the optical fiber drones which come in spool lengths up to 20km…