Where is the Catalina setting to move the mouse between two monitors?

During initial setup of a 16" MBP w/ Catalina, there was an option to move the mouse between two screens--it was not the thing where you use an iPad. It was going to search for another computer on the same network, and by taking mouse to either the far left of right of the active MBP, it was going to pop over to the adjacent, connected device.

Now I want to enable this, and cannot find it anywhere!

1) what is this called?

2) where is it?