OK, OK, there are still rules, but they’re less strict. Now you can fine-tune the size of text within individual apps—a move that isn’t flashy but could change the way you use your phone.
At its core, the aptly named Text Size widget is one of several accessibility tools that gained expanded capabilities when Apple rolled out the latest version of its mobile operating system. Use it, and you likely won’t have to deal with any apps displaying awkwardly due to whatever OS-wide text size you have in place. And you certainly won’t have to be as frustrated with people who send documents stuffed with teeny, tiny font (you can still grump at them, though).
You can only unlock the incredible power to shrink and grow text at will via the Control Center. To get there, open the Settings app, tap Control Center, and find the Text Size option. Tap the green plus sign next to it to add it to the list of active tools. You can also touch and drag the three lines to the right of each item to rearrange how they appear on the screen.
Before you leave this settings page, make sure the Access within apps toggle switch at the top of the screen is turned on. If it’s not, you will open the Notification Center instead of the Control Center when you’re using an app.
With the foundation laid, go to any app and open the Control Center by swiping down from the top right corner of the screen (or up from the bottom if your iPhone has a Home button). Tap the text size icon (two capital A’s of different sizes) and you’ll see a sliding scale.
“Make text big” and “make text small” seem like pretty straightforward abilities, but Apple’s tool can be a little finicky at times. For one, the “within current app” and “across all apps” changes occur independently. So if you previously set one app to have text that’s 160 percent bigger than normal and then decided you liked everything to be 135 percent larger, that first app won’t match until you open and use the widget inside that troublesome app.
It’s also worth noting that because icons and buttons aren’t text, they won’t change size with the words on the screen. And while the changes will take effect immediately in some apps, like Twitter and Apple’s own Messages app, you may have to reload others to see a difference. Beyond that, it’s up to you to decide what satisfies your needs. Because here—for once—size really does matter.
Source : https://www.popsci.com/diy/change-app-text-size-ios/