Place _layouts/...
after the site name in the URL.
Examples:
https://company.sharepoint.com/_layouts/settings.aspx
https://company.sharepoint.com/sites/somesitename/_layouts/settings.aspx
Stubs:
- Classic Admin Centre -
https://<your tenant name>.sharepoint.com/_layouts/online/tenantsettings.aspx
- Site Setttings -
_layouts/settings.aspx
- Site Contents -
_layouts/viewlsts.aspx
- Site Permissions -
_layouts/user.aspx
- Site Collection Administrators -
_layouts/mngsiteadmin.aspx