In Zoom on Windows I go to Settings > Video > check Turn off video when joining meeting
I'm pretty sure that will stop anyone from forcing my camera on. But I think that setting defaults to unchecked, meaning by default Zoom automatically shows your video.
For extra protection:
Settings > Audio > uncheck Automatically join audio by computer when joining a meeting
Settings > Audio > check Mute my microphone when joining a meeting
Settings > Audio > uncheck Press and hold SPACE key to temporarily unmute yourself.
I also generally join a bogus empty meeting before any real meeting to preview and ensure my microphone, webcam, virtual background, filters, and studio effects are all the way I want them and not something silly from some playful meeting yesterday.
For this reason I always keep my laptop Mike volume to 0, and use the mute button on my headset which is not computer controlled. And an external webcam which I can plug in when I want to.