Screen-share from iMac to MBP

[jasnw]

I want to be able to screen-share an MBP (Catalina) from an iMac (El Capitan) and have the screen size of the MBP appear as though it were in clamshell mode attached to a 27" monitor. I've been using that exact setup (with a monitor) which works just fine, but once the monitor is gone (which it now is) the screen-share goes back to the size of the MBP. Is there any way to force the MBP to think it's projecting to a larger physical screen?

 

[Juicy Box]

I don’t think so, at least built into macOS. There is a third-party software that I used before the change monitor resolutions, I can’t remember the name of it. I use it on my 17 inch late 2011 MacBook Pro, when I get a chance I’ll take a look and see what it is called.

 

[maflynn]

Is there any way to force the MBP to think it's projecting to a larger physical screen?

I think you're asking about Target Display Mode - using the iMac as a display. If you are, then you may be able too. See this: Use your iMac as a display with target display mode

If you're wanting to use remote control, i.e., use the iMac to remote into the MBP, then can use one of these methods:
3 Free Ways to Remotely Connect to Your Mac’s Desktop

 

[jasnw]

Target Display Mode would probably be the trick, but my iMac is on El Cap (HS or better is required) and my MBP is too new. I'm hanging on with this old iMac (2011) waiting for Apple to bring either an Mx-chip replacement for the high-end Intel Mini or an Mx 27" iMac to the market, so I don't want to spend time/effort upgrading to HS, otherwise I'd upgrade and give it the old college try despite the "too new" MBP.