So my 2018 MacBook Air can drive the Apple LG 5K display (lid closed) at 5120 x 2880 at 60Hz.

https://support.apple.com/en-us/HT210205

I currently have the Apple LG 4K but plan to upgrade to the 5K.

I agree with you on the just works thing. I have the same keyboard, trackball, monitor, tbolt dock and external HD on my desk at home and work.