Find and select your iPhone "Settings" app.
Scroll down and select "Accessibility."
Find and select "Display & Text Size."
To expand your font size options, you must first turn on" Larger Text."
Switching on "Larger Accessibility Sizes" will give you a greater range of font size options from which to choose.
Use the scroll at the bottom of the screen to select the appropriate font size for your iPhone's text.
You should see the font size above change simultaneously with your selection.
Recently, I've been playing a lot of Diablo Immortal on my iPhone, which means tiny dungeons and tiny gameplay. While I love mobile gaming, sometimes it can cause eye strain.