How do you enable universal control macos monterey

In addition to what dialabrain said: if you add your iPad as an additional screen to your mac, then universal control would not be called upon, anyway; your cursor will move to it just like any external display, as it has since maybe 1987 (when Macintosh II first allowed for more than one display in a mac - yes, I am old 😎)

Universal control, when it comes, will allow for a single mouse or trackpad, and keyboard, to control separate devices seamlessly-ie you would still be using the iPad per se but could control it with the mac keyboard and trackpad. Pretty amazing but is probably harder than expected to make it work reliably, and hence it has been pushed back to a later Monterey update.

Universal Control is not ready for prime time just yet.