What monitor and screen resolution to work with Cubase?

Hello! I plan to buy a new monitor that will be used mostly for Cubase. I am considering a monitor with a resolution of 3440x1440 or 2560x1440, 27 or 32 inches. I am currently working on the INTEL UHD630 graphics card. Are there any problems with Cubase with these resolutions? Will I need an additional graphics card? Thank you and best regards!

Cubase should work just fine with those.
The issue you may have is size on some non-scalable elements but that also depends on how far the mnonitor is away from you nad how goiod your eyes are. FWIW I use two 24" monitors at 1920*1200 each.

You’ll need to check the spec of your Video card, that should give you the maximum resolution it can support.

I have 43" 4k TV for main window plus 24" Full HD monitor for mixer view and everything is crystal clear

Any resolution/size that does not need upscaling works beautiful.
I use 2 * 2560x1440, 27inch set at 100% scaling, hidpi on. Nice and sharp.