What a low camera actually communicates
A lens below your eye line points up. That gives an unflattering angle, but the more important effect is behavioural: to read faces on the screen you look down, so everyone else sees the top of your head instead of your eyes.
Raise the lens to just below eye level and the geometry inverts. Now looking at the screen means looking roughly into the camera, which reads to everyone else as attention. No software or filter substitutes for that.
The right height and distance
Put the camera between your eye line and about 5 cm below it, roughly an arm's length away. Frame yourself with a small gap above your head and your shoulders visible; anything tighter feels confrontational, anything wider makes you a small figure in a room.
For phone calls specifically, portrait orientation crops the room out and works well for one-to-one conversations. Landscape suits meetings where you want to look like the other laptop cameras in the grid.
Why the book stack fails
A stack of books works for exactly one call. It is unstable, so you protect it with your posture and never lean on the desk. It cannot be adjusted mid-call. And it has to be rebuilt every time, so most days you skip it.
A stand solves the repeatability problem, which is the real problem. The setup you use is the one that requires no setup.
Light beats hardware
Face a window or put a lamp behind your screen at face height. Never sit with a bright window behind you — the camera exposes for the window and turns you into a silhouette.
With good frontal light, a phone camera at the correct height will out-perform a mediocre webcam in a badly lit room. Order of investment: light, then height, then hardware.
Sound, hands and the last details
If your device is now at eye level and further away, its microphone is further away too. Use earbuds or a headset for anything longer than a quick check-in.
The underrated benefit of getting the device off the desk is that both hands come free. You can take notes, type, or gesture while talking — and gesturing on camera makes you noticeably more engaging than sitting still with your hands in your lap.