best way I’ve seen is to set your game to Windowed mode, and then in game set the resolution of the game to run at the client’s. Not super if you frequently move around, but if you always play one game from one client, at least it’s always a “per game” setting.
If you want a real challenge and want to have it a very specific way… a very fun nerd project is setting up VMs with GPUs that can run Steam, and those can always have a specific resolution. I did that for a while, it was a ton of fun, and a ton of wasted time because I just wanted to do it