There are a few, third party software programs, that you can use to enable split screen on PC.

This is the top one that came up in a basic websearch:

https://universalsplitscreen.github.io/docs/guides/dst/#:~:text=Split%20screen%20setup%20Install%20and%20run%20Universal%20Split,screen.%20You%20should%20now%20be%20able%20to%20play

Here's a different program that came up in a YT search:

https://www.youtube.com/watch?v=xMotL2DSeBA