larger display would create unwanted echoes and reflections ?
True !
Of course, as Tetsujin writes, like any other surface in the field of the sound source(s) would.
you would never find a serious studio with large things, including
large displays.
Because reflections also depends on the volume of the room, I presume this will be true for small sized serious studios only.
Then as with any other parasitic source of whatever, the question being : How much do you care ?
I can understand that if you spent a lot, sacrificed the esthetics of your home, in order to build a truly anechoic chamber, you'll be reluctant to spoil your work with whatever object.
Because the unwanted effects of most reflections can be significantly diminished changing the position and orientation of objects, the larger the screen is, the more difficult changing position and orientation is. This is the reason why I personally prefer several "small" screens to a big one.
After all, and as usual in so many disciplines impacted by parasitic effects, everything depends on the way you work :
Either you invest a lot in upstream work (building the theoretical idealistic studio) which needs a good knowledge in physics, and you even don't need any screen at all or…
You invest a lot in post-processing since everything including fine denoising can finally be achieved that way.
You'll then need a good knowledge of the available plugins, a fair knowledge in computer programming, strong processing power... and… big screens.