We have a room like that. We put a window fan in front of the vent to pull in the cool air from the AC.

I have a similar situation that went un noticed until I started working from home. Its a corner room with walls facing east and south. A good portion of heat is reflected back to our house from the neighbors white garage about 20' away. I keep the blinds on that SE side closed and a fan on to keep air moving. I'm looking for fast growing, narrow evergreens.

Have you thought about adding an air return in the room so the HVAC can pull the hot air put of the room?

I have 2 rooms like that in my house, and they’re over the garages and face west. We tinted the windows which helped slightly, but unless we did some kind of garage insulation, it doesn’t fully solve the problem. They’re hot in the summer, and cold when we have cold days (which isn’t much in south Florida).

We had a room like that and turns out the damper to the room was not working properly so very little cool air was getting to the room.

Can you tell whether the same amount of cool air coming out of the vents, as the room beside it? If not check the dampers, they may not be fully open.