Why is my landscape painting rigid and "square"?

Hey BIGTIMEMASTER, thanks for your help.
However, when I follow the steps as you laid out, I can tell that the vertices are changing, but they aren’t necessarily increasing. What people have meant when they say “increase the resolution” is using the settings when first setting up a landscape to do so (such as ‘section size’, and quite literally, the ‘overall resolution’ setting). My issue is that even on the highest setting (8161x8161 vertices) in there I see a very miniscule difference to even the lower settings.
UE5_LandscapeSettings