You simply can’t do that in SQL. You have to explicitly list the fields and concat each one:
SELECT CONCAT(field1, "https://stackoverflow.com/"), CONCAT(field2, "https://stackoverflow.com/"), ... FROM `socials` WHERE 1
If you are using an app, you can use SQL to read the column names, and then use your app to construct a query like above. See this stackoverflow question to find the column names: Get table column names in mysql?