Yes, go to site settings site columns > create the column, once this is complete either go to content type publishing hub or site content types in site settings and edit the content type there adding the column you have created

this should be fairly straight forward, edit the library permissions, stop inheriting and then add a group that has contribute level permission, if this is done at the site level the will have contribute permission to all the libraries including site pages and pages which will allow them to edit those respectively.