I wanted find patternin string and replace that pattern wiht other

Alter FUNCTION dbo.RecursiveReplace_fn1
(
    @P_String VARCHAR(MAX),
    @P_Pattern VARCHAR(MAX),
    @P_ReplaceString VARCHAR(MAX),
    @P_ReplaceLength INT = 1
)
RETURNS VARCHAR(MAX)
BEGIN
    DECLARE @Index INT;

    -- Get starting point of pattern
    SET @Index = PATINDEX(@P_Pattern, @P_String);

    IF @Index > 0
    BEGIN
        -- Perform the replace
        SET @P_String = STUFF(@P_String, PATINDEX(@P_Pattern, @P_String), @P_ReplaceLength, @P_ReplaceString);

        -- Recurse
        SET @P_String = dbo.RecursiveReplace_fn1(@P_String, @P_Pattern, @P_ReplaceString, @P_ReplaceLength);
    END;
    
    RETURN @P_String;
END;