You asked in the wrong board, this is for AUTOCAD, not for "AutoCAD for MAC"
Look here for the right board: https://forums.autodesk.com/
And: Please use the HELP[F1] first, if you didn't find the answer, search in (the right) Forum,
at last, ask other users in (the right) forumboard.
EDIT: Oh, a new member - SORRY, welcome to the community 🙂
Here is the answer for what you asking for: Multiline Styles cannot be create in AutoCAD for Mac
http://help.autodesk.com/view/ACDMAC/2021/ENU/?guid=GUID-9D1491EB-6B6A-4F7A-9548-FC5A1346593A
