here is an example of how to use the spread operator in a UDF:

CREATE OR REPLACE FUNCTION udf__multiply(a NUMBER DEFAULT 1, b NUMBER DEFAULT 1, c NUMBER DEFAULT 1, d NUMBER DEFAULT 1)
RETURNS NUMBER
AS
  $$
    a * b * c * d
  $$
;

-- Spread Operator to convert the array into individual arguments
SELECT udf__multiply(**[1, 2]);
-- Returns: 2

SELECT udf__multiply(**[1, 2, 8]);
-- Returns: 16

SELECT udf__multiply(**[1, 2, 10, 10]);
-- Returns: 200