Please, read the documentation.
And yes, cache can be enabled/disabled whenever you want.
The best way to learn: TRY IT!
Please, read the docs, play with Nginx before asking. Nginx Cache is a little bit more complicated than you think.
I think these two commands are used to toggle the NGINX and Redis cache.
sudo site example.com -cache=on
sudo site example.com -cache=off
You also have to deactivate/active the cache plugins.
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