During the migration from your SharePoint on Premises environment towards the SharePoint Online environment you discover that you couldn´t create an Enterprise Wiki as that one is missing.
According to Microsoft here, the “Publishing tab will not appear if the publishing features are not enabled at the site collection level. Your site collection administrator needs to enable the SharePoint Server Publishing Infrastructure feature on the site collection to make publishing-related templates available in the site.”
But if you as an owner from the website collection go to site settings -> Manage site features and try to enable the “SharePoint Server Publishing” you got the following error:
The feature being activated is a Site scoped feature which has a dependency on a Site Collection scoped feature which has not been activated. Please activate the following feature before trying again: SharePoint Server Publishing Infrastructure f6924d36-2fa8-4f0b-b16d-06b7250180fa
The Site scoped feature being activated has a dependency on hidden Site scoped feature 'FeatureDefinition/15/22a9ef51-737b-4ff2-9346-694633fe4416' (ID: '22a9ef51-737b-4ff2-9346-694633fe4416'). Hidden features cannot be auto-activated across scopes. There may be one or more visible Site scoped features that auto-activate the dependent hidden feature.
The Site scoped feature being activated has a dependency on hidden Site scoped feature 'FeatureDefinition/15/dffaae84-60ee-413a-9600-1cf431cf0560' (ID: 'dffaae84-60ee-413a-9600-1cf431cf0560'). Hidden features cannot be auto-activated across scopes. There may be one or more visible Site scoped features that auto-activate the dependent hidden feature.
The solution here is quite simple:
You as an owner from the website collection can manage some features, however not the “SharePoint Server Publishing Infrastructure” you require here. This can only be done by the website collection administrator. So login as an website collection administrator and go to site settings -> site collection administrator -> site collection features and enable the “SharePoint Server Publishing Infrastructure”. Once done you can create a new subsite and see the publishing tab which now included also the Enterprise wiki.
A SharePoint user with owner / full access rights can only enable / disable the “SharePoint Server Publishing” feature for subsites however he do not have rights to enable the “SharePoint Server Publishing Infrastructure” on the website collection.