What to do when Gmail is full?

Question

gmail

Hello comrades, I actually encountered the most common problem, the volume of mail gradually approached 15 available free GB.
What to do next? Is it possible to increase the volume without resorting to paid methods for solving the problem?
Actually the whole problem is that you still need to have access to the old mail. I ONLY use the web interface, is it possible to somehow transfer the mail to another address, but be able to search using the old mail?
Sorry if it's messy.

Answer 1

By imap, transfer all letters to another box, and that's all.

Answer 2

Google sometimes gives out additional space. My limit is 19. Security check passed once a year and 2GB as a gift.