Every page on this site has three small letter A buttons near the top, one small, one medium and one large. Tap whichever one is comfortable to read. The writing gets bigger or smaller straight away.
Only the writing changes. The menus, the buttons and everything else on the page stay the same size, so nothing moves around underneath you while you are reading.
Your choice is remembered. Open another page and it is already set the way you left it, and it stays that way the next time you visit. It is remembered by your own phone or computer, not by us: nothing about how you like to read is sent anywhere.
If you clear your browsing data, or you read on a different phone, the size goes back to the middle setting. Just tap the size you want again.
Poems use slightly larger type than articles do, at every one of the three settings, because a poem is meant to be read more slowly.