Yes, you can! Just go to "Room Details" in the settings icon and scroll down to "Permissions" and toggle "Camera" or "Mic."
When enabled, people entering your room will be allowed to use their camera or microphone. When turned off, people entering your room won't be allowed to have their cameras or mics on. (In the photo above, the camera and mic are turned on, meaning visitors will be able to use their camera and microphones.)