In the setup I use I have the following 3 devices:

1. iMac 27" late 2015 with OpenCore Legacy Patcher Sonoma: 14.1.1
2. MacBook Pro 15" late 2016 with OpenCore Legacy Patcher Sonoma: 14.1.1
3. iPad 10.2" 7th Gen with iPadOS version: 17.1.1

They are connected to the same WiFi network.

Steps:

1. On the iMac go to: System Settings -> Displays
2. Click the plus sign to the right of the Built-in Display
3. Choose under Mirror or Extend to: MacBook Pro
4. Choose under Link keyboard and mouse to: iPad
5. You now see the 3 screens under Displays, but it is not yet extended across all 3
6. Click on the iPad
7. Choose for the option: “Use as” - select: Extend or mirrored display
8. You now see the same desktop on all 3 devices
9. And you can drag applications from the iMac to the MacBook or the iPad