Camera needs to lock to the right of the player character using RunService:RenderStepped, and player movement needs to be ignore 1 dimension (1 axis, either X or Z).
There used to be a top-down tutorial on developer.roblox.com but it may not be available any more.
Simply put, yes, everything can be made in 3D. NPC’s, obstacles and platforms, everything. Just constrain movement to 2D (so ignore one dimension, one axis).
AND a correction:
Studio > File > Open From Roblox
Then click New, then choose the