Time Signatures (unusual)

I know this title may sounds stupid but, it’s not what you think. In Ligeti’s Piano Concerto, the piano’s time is ¹²/₈ while the orchestra is ⁴/₄.

Welcome.
Polymeters like this are quite common. Even Bach used them!

You can reproduce them in Dorico, but it does require the use of hidden tuplets.

There’s a great thread you can search for about setting Bach’s Jesu Bleibet. What you do is set contrasting (by holding alt) time signatures for the first measure, and then use hidden tuplets the rest of the time (which can be copied and pasted to help save time).

Welcome to the forum @LaTonya_Hutchisom !

There’s also this article on Scoring Notes on the same topic: