Webcam or camera for video calls?

Resolution is rarely the problem. Almost every bad video call comes down to light and camera angle.

Four routes

Laptop camera for internal calls, external webcam as the best effort-to-benefit point, phone for recordings, DSLR only if you record regularly.

A Logitech MX Brio and, more importantly, a small LED panel. Light beats camera.

If picture and sound compete, sound wins. Buy the microphone first.

FAQ

Is the laptop webcam enough for client calls?

Fine internally. For client calls it is the weakest option: it films from below and gets grainy in low light.

Do you really need 4K for calls?

No. Most conferencing compresses anyway. The benefit of a good camera is the sensor and lens, visible in poor light rather than perfect conditions.

Better camera or better light?

Light, by a wide margin. Turn your desk so the window is in front of you, not behind. That costs nothing and works immediately.