The line of sight will depend on the distance from the transmitter. If it's nearby such as within a mile or two, it will may work fine with minor obstructions such as a tree or wall in the path, much like how 5GHz Wi-Fi can still penetrate walls. Most WISPs here operate on 3.6GHz (licenced) or 5GHz (using the 5GHz Wi-Fi band.)
If the transmitter is far away such as 10+ miles or operates above 6GHz, it will need clear line of sight of the transmitter. This is a problem the new wideband 5G cells face where anything in line-of-sight blocks the signal, such as going indoors. For example, all the 5G speed test demos are carried out either outdoors or in a cellphone shop that has an indoor 5G node.