With some REPLACE in 1.2.3.4 to get [1,2,3,4] you can simply use JSON_EXTRACT:
SELECT
JSON_EXTRACT(ip.column1, '$[0]'),
JSON_EXTRACT(ip.column1, '$[1]'),
JSON_EXTRACT(ip.column1, '$[2]'),
JSON_EXTRACT(ip.column1, '$[3]')
FROM (
VALUES('[1,2,3,4]')
) AS ip