I was wondering, if its possible to give specific people permission to submit / decline access request to recources, without being the owner of the whole SharePoint?
The SharePoint is seperated in different libaries from different teams. Every libary has an admin, who has full access to the libary, but not to the whole SharePoint. So when someone sends an access request for a recource from the libary, the admins from the libary cant submit it, just the ownwers of the whole SharePoint.
The best way would be, that every admin can submit the access requests for their own libary.
Another good solution would be that every admin from the libaries could submit all access requests, without become the owner of the whole SharePoint.
The built in access approvals list is accessible only for Owners. You may need to build a custom process letting individual library admins to submit access requests on behalf of users. Alternatively you can let users request access if and when they get access denied by updating 'Allow access requests' option Advanced permissions settings for the site.