How to change Window Size smaller than app will allow?

[saint01]

I apologize if I didn't see a duplicate of this post, but I am trying to make the window of my Signal app smaller, as the external screens I am using on my M1 MacBook are only 1920x1080. The window, even at the smallest that the app will allow, will still not condense to a more manageable size. Sure, I can buy new $300 screens, but my dell's work very well and I am thinking that there must be a way to override these limitations, whether in the plist file for Signal, or elsewhere. I do not want to set a global standard, but just adjust an app at a time to make the windows themselves on the OS smaller. Anyone addressed this successfully?