While VNC uses the terminlogy of server for the remote system and viewer for the local system - it is more like an opposite view of the server/client method.
We are used to the remote system to be serving us something - either a webpage or sending a mail and the client is consuming the data or service.
With VNC it is opposite - your workstation becomes the server as it is serving kbd, mouse and monitor to the client - the Pi.
The VNC service in the Pi is reacting to the servers kbd and mouse and in return sends back the images generated by the client to the server. The images you see on your workstation is generated by the Pi and sent over the wire - and the quality of the connection greatly influence the quality of the recevived images.
You can modify the viewer connection options for the vnc server on your workstation but in any case the image is generated on the Pi. My RPi4/8GB (Ethernet) streams FHD over SSH without any loss of quality. TigerVNC doesn’t transmit audio.
The original RaspberryPi OS comes with RealVNC - a courtesy of RealVNC towards the RaspberryPi project.
As this is a commercial version of VNC you may be able to tweak it further.
But if your intention is to stream movies then a better solution is to use RTSP directly from the PI to e.g. VLC.
This is one of the ways to use the raspberry pi as surveillance camera.