how to search for string starts with % itself for example %john , name is started with % itself

Answer 1

You can escape wildcards using the ESCAPE statement, e.g.
SELECT login FROM users
WHERE login LIKE '/%%' ESCAPE '/'

The first % is escaped and therefore treated as a literal, while the next one functions as normal.
The result is a search for strings that start with the character %.

Answer 2

your escape slash is inverse