Can i stream one mac to another via wire?

Hello Billy-Cooper,

You may find some helpful info on sharing the screen of another Mac here: Share the screen of another Mac - Apple Support

Start a screen sharing session with another Mac

If you’ve been given permission, you can view and control the screen of another Mac on your network.

1. On the Mac you want to share, choose Apple menu  > System Settings, click General  in the sidebar, then click Sharing on the right. (You may need to scroll down.)

2. Turn on Screen Sharing, then click the Info button  on the right.

3. Note the name and address of the Mac (it’s listed at the top), then click Done.

The name looks like “iMac (7)” or “Joe’s MacBook Pro.”

The address looks like vnc://[IPAddress] or vnc://[Name.Domain].

4. On your Mac, do one of the following:

Connect using the name: Click the Finder icon  in the Dock to open a Finder window. In the Locations section of the sidebar, click Network, double-click the Mac you want to share, then click Share Screen.

If no items appear in the Locations section of the sidebar, hold the pointer over the word Locations, then click the arrow .

Connect using the address: In the Finder, choose Go > Connect to Server, enter the address of the Mac you want to share, then click Connect.

5. If prompted, enter your user name and password, then click Sign In.

If both computers are logged in using the same Apple ID, the screen sharing session starts. If they’re not, you’re prompted to enter the user name and password of a user who is allowed screen sharing access on that computer, or you can request permission to share the screen if the computer allows it.

6. If someone else is already connected to the Mac as a remote user, a dialog asks if you want to share the display with the other remote user (Share Display) or log in concurrently using a different user name and screen (Log In).

If you choose Log In, you share the Mac with the other remote user, but you won’t share the same screen.

Cheers.

Hello Billy-Cooper,

Welcome to Apple Support Communities!

We want to help you get the most from your devices.

You might be able to use target display mode with an iMac if your devices meet the requirements.

See here:

"iMac models introduced in 2011, 2012, 2013, and mid 2014

To use any of these iMac models as an external display:

• The iMac used as a display must have macOS High Sierra or earlier installed.
• The other Mac that you're connecting it to must have been introduced in 2019 or earlier and have macOS Catalina or earlier installed.
• The cable connecting the two Mac computers must be a Thunderbolt  or Thunderbolt 2  cable.

24-inch and 27-inch iMac models introduced in 2009 and 2010

To use any of these iMac models as an external display:

• The iMac used as a display must have macOS High Sierra or earlier installed.
• The other Mac that you're connecting it to must have been introduced in 2019 or earlier and have macOS Catalina or earlier installed.
• The cable connecting the two Mac computers must be a Mini DisplayPort  cable.

How to use target display mode

1. Make sure that your iMac is started up and meets the system requirements above.
2. Make sure that the other Mac is started up and logged in to a macOS user account. 
3. Connect the two computers using the appropriate Mini DisplayPort or Thunderbolt cable. 
4. You can use more than one iMac as a display, if each iMac is using a Thunderbolt cable to connect directly to a Thunderbolt port on the other Mac (not the other iMac). 
5. Press Command-F2 on the keyboard of the iMac. You should now see the desktop of the other Mac.
6. To exit target display mode, press Command-F2 again. Or disconnect the cable, or restart either Mac.

Apps that were open on your iMac when entering target display mode remain open in target display mode. For example, if you begin playing music on your iMac and then enter target display mode, the music doesn't pause on your iMac.

The other Mac can't use the iMac computer's built-in camera or ports. To use external devices with your other Mac, connect them directly to the other Mac, not to your iMac."

This Apple Support page has the full details: Use your iMac as a display with target display mode - Apple Support

We hope this helps. Please let us know if you have further questions.

Cheers!