I’m trying to optimize a query to remove the scalar valued function that returns a comma separated list. I’ve read online that making it inline should benefit performance. Could someone please help with making my UserDefinedFunction inline or recommend how to improve performance?

-- Description: Returns a comma separated list of Tags for a defined Course Enrolment
--      
-- =============================================

/****** Object:  UserDefinedFunction [dbo].[fn_ConcatenateCourseEnrolmentTags]
CREATE FUNCTION [dbo].[fn_ConcatenateCourseEnrolmentTags] (@ClientOfferRegID As int)  
    RETURNS nvarchar(3999) AS  
BEGIN 
    DECLARE @Desc nvarchar(3999)

    SELECT @Desc = IsNull(@Desc + ', ', '') + dbo.tbl_Tag_Shared.Name
FROM         dbo.tbl_Tag_Shared INNER JOIN
                      dbo.tbl_Record_Tag ON dbo.tbl_Tag_Shared.TagId = dbo.tbl_Record_Tag.TagId INNER JOIN
                      dbo.tbl_Entity ON dbo.tbl_Tag_Shared.EntityId = dbo.tbl_Entity.EntityId
WHERE     (dbo.tbl_Entity.ObjectId = '06') AND (dbo.tbl_Record_Tag.RecordId = @ClientOfferRegID)
ORDER BY dbo.tbl_Tag_Shared.Name
    
    RETURN @Desc
END

GO

        SELECT
                    tbl_Client.ClientID AS LearnerId, 
                    tbl_Client.FirstName AS LearnerFirstName, 
                    tbl_Client.LastName AS LearnerLastName, 
                    dbo.fn_ConcatenateCourseEnrolmentTags(tbl__Client_Offer_Reg.ClientOfferRegID) AS Tags,
        FROM        
                    tbl_Client
                    ...
        GROUP BY    
                    tbl_Client.ClientID, 
                    tbl_Client.FirstName, 
                    tbl_Client.LastName,
                    dbo.fn_ConcatenateCourseEnrolmentTags(tbl_Client_Offer_Reg.ClientOfferRegID),