Do I need to explicitly grant permissions for a login under the sysadmin role for it to access a custom schema? So I have a login that has sysadmin rights on the db server.  However, it's not able to access database objects under a custom schema that was created (eg. it cannot select from tables with [custom_schema].[table_name]).  Do I need to explicitly grant permissions for this login to the custom schema even though it is part of the sysadmin server role?  If that is the case, do I simply run the following if I want it to have db_owner rights to my custom schema?

GRANT TAKE CONTROL ON SCHEMA :: [custom_schema] TO [login];

Thank you in advance!
No, members of the Sysadmin role or the database owner role bypass the permission checking algorithm. So no matter what permission are granted or denied , they are able to always access the objects.