Can I share my MacBook Pro 2020 screen to my iMac 2011?

The feature to allow the use of an older iMac as a direct, hardware-accelerated display has been deprecated for MacBook Pro AFTER 2019 models.

You can use built-in Screen Sharing to show the screen of another Mac in a window.

Data are transported across your network, so if you have a poor connection only over Wi-Fi, it can be slow. I use 10G Ethernet to share the screen of my Mac Server in another part of the house, and it works great for that purpose.

https://support.apple.com/guide/mac-help/share-the-screen-of-another-mac-mh14066/10.14/mac/10.14

Ask the MacBook community? This one’s for Apple displays only.