I just use the defaults, but you might be able to do something with auto commands.
Detect when the window you want opens and resize it with the regular vim commands or lua.
That's a good idea. Really the problem is that the repl is too narrow so it might not be too hard.
I see. Yeah that can sometimes be annoying, but I personally find in my debug sessions that I don't use it a lot. There's just a lot of windows if you activate the debug ui.
What helps me is using a different tab to set breakpoints and browse my code. In the debug view I resize my windows so that the code browser only shows a very small window so that I can see where it jumps around. Code that I want to actually read is in the other tab.