How to get more storage without paying?

If you mean how can you pay for it without using your payment method such as a credit or debit card, etc., you can buy Apple Gift cards and redeem them. You can pay for the storage that way. Your Apple ID balance will always be used for purchases before your card is used.

If you are looking for a total freebie, that’s not going to happen as stedman1 has already told you. Someone has to pay for it. Apple doesn’t give it away.

How do you get more storage with out paying

You delete apps, music, video, pictures and other things that you no longer need from your phone.

Without further details the only possible answer would be: you don’t.