Currently, existing pages have the levels "edit", "move", "delete", and "protect". The latter two are rarely seen due to sysop being the highest level on most wikis. However, on wikis where this is not the case, it's possible to set the Delete and Protect level.
For nonexistant pages, there is "Create" option. However, there needs to be a "Create" option and a "Protect" option, to prevent simply lowering the protection level and entirely bypassing it.
You should use TitleGetRestrictionTypes hook to add more restriction types that you want.
I'd not advise you to wait for this to be added in core, if you truly need it. Because that could take forever to happen. Please explain why you cannot use the TitleGetRestrictionTypes hook that I mentioned above, to achieve the same thing for your install.
Mainly because I don't see a reason to run around using extensions for something that actually affects ALL wikis. However it might be worth looking into for a short term solution
A demonstration of this bug is now available at https://test.miraheze.org/wiki/User:Dmehus/Create_protection_known_issue
It appears that this is now fixed, with the create option also applying to protecting it.