Change letters before changing the whole interface
Text size and display size are often separate settings. Text size mainly changes supported lettering, while display size changes the scale of more of the interface. On Android, Google's accessibility guidance suggests searching Settings for Font size or Display size; the exact arrangement depends on the phone.
Move one setting by a small amount, then open a message, a long article, and a settings screen. Look at line breaks and whether a button has moved below the visible area. A preview inside settings is useful, but it cannot represent every app you use.
If text still feels hard to distinguish, try the available bold-text option separately. Do not assume that making everything larger is the only useful change. Contrast and the font used by a particular app can matter, and some apps do not follow the system's text setting.
For a browser article, page zoom or a reading view may be a better local adjustment than changing the whole phone. Check whether that preference applies to one website or all websites. You want the next page to behave in a way you can predict.
Keep the controls reachable
Open the keyboard and type a short message after changing the display scale. Check the send control, attachment button, and any lower navigation bar. If a dialog seems to have lost its confirmation button, try scrolling within it before reducing the setting immediately.
Take a screenshot or make a note of the original setting before experimenting, especially if you are helping someone else. Show them how to return to the control and let them choose the comfortable size. A setting that looks tidy to the helper may still be too small for the person using the phone.
Try the arrangement for a normal day. If only one app remains difficult, inspect that app's own display options or accessibility support. Repeatedly shrinking the entire phone to accommodate one poorly arranged screen can undo the benefit everywhere else.
Keep the adjustment modest enough that you can navigate confidently, then increase it if necessary. There is no prize for fitting the maximum number of lines on a small display; the useful result is reading the message without losing your place or guessing at a control.
