@hotdeer Hello! @PipMenace is correct. It's Shift Tab for PC / Mac in both camera modes. It's press and hold right stick (R3) on PS4. There's a right-click (circle button) option on doors to get in and out of rooms. I can right click (circle) to go to a point downstairs but you sort of have to know where to click. I haven't been able to find a way to go upstairs in first-person.
By the way, I don't have a PS5 but it's probably the same as PS4. It should be the same on Xbox as well; hold right stick (RS) to enter/exit first-person. The B button is the equivalent of the PS circle.
