How do I upscale a 1080p only game to my 4k monitor?

[Tiger]

I'm new to the software.

[Gizzmoe]

Run that game in Windowed or Borderless mode and use the LS1 scaler to bring it back to Fullscreen, Scaling Mode Auto.

[Zef]

What Gizmoe said.

Image quality will be worse though if you jump from 1080P to 4K.

For best results you always do an "X2" of resolution.

720P to 1080P, 1080P to 2K, 2K to 4K