some more insight
so it turns out this only mostly works. the player can still clip the camera inside of the walls if they want to and see things they shouldn't. so there are two solutions:
1) heavily restrict player camera or use fixed camera angles
2) paint black on the opposite side of the walls
i'm going with number 2 for now and it seems to mostly work. there are a couple seams i have to add additional black walls to at odd corners here and there but that's not a huge issue.
the engine's camera doesn't respect collision, but i haven't messed around with camera settings too much so maybe there is a way to force that i'm not seeing yet.
for my actual game instead of this test project, i'm thinking of three different camera modes. first person, fixed cameras, or a top-down camera you can simply rotate/zoom. that way the player won't be able to move the camera in ways that appear glitchy.
first person is the last thing i want to go with because i just kind of wanted to make it third person like classic survival horror games. if i go with the top down perspective, it'll likely be something like what you see in the photo in the previous post. from that angle and distance, but with the ability to rotate the camera around freely. in fact, maybe i'll just do that for this test project too. i love the idea of having a super dynamic camera but it does come with its own share of issues.
some more insight
@coded_artist technically it is Godot but it's an engine that is built with Godot. It's called RPG In A Box.