Another option, if you want to add the columns permanently
Join Field—Data Management toolbox | ArcGIS Desktop
As Dan mentioned, do the excel-to-table first, and I would use the add-join (or Add Relate ) to test the results (both which can be temporary, or at least do not permanently/physically add the fields), but then if you want it permanently added to you table, use the Join Field to add the columns to the in_data....you can also filter for just the columns you want. The in_field and join_field do not have to be the same name, but do need to have equal values (which is why testing first is helpful.
JoinField_management (in_data, in_field, join_table, join_field, {fields})If the columns do not add correctly or you get too many fields added, you can always use Delete Field—Data Management toolbox | ArcGIS Desktop
Keep in mind that if you add fields, and there is already a field with that name, the new fields will get a _1 added to the new fieldname (at least in Desktop...assuming same in Pro)
Just some options...but I would go with Dan's suggestion first.
