Is it ok to hide the full settings until initial onboarding steps are complete?

Hiding settings would be a forced onboarding. users will not be going to stay longer either they will not like the product so it's good to give them flexibility while onboarding. only thing you can do is to add guidance. a guided onboarding is considered good.it also helps your users to make less errors.

Making the settings available only after having completed an onboarding does not seem a good solution. You are afraid that users will be lost when confronted with these settings. But to force the user to complete an onboarding seems quite patronizing.

It always should be in the users choice how to proceed.

Onboarding is not always a good solution either. It might be better (maybe in addition) tho provide guidance where it is needed (interesting article on onboarding https://www.nngroup.com/articles/mobile-app-onboarding/ )

So what I would suggest, is an approach that hides the additional settings for example in an expander, something like "pro mode". On showing them give the user specific guidance per setting or if necessary for a group of settings.

If you do an onboarding keep in mind that a user has to remember all the information given in the onboarding.