Find the font-size control
Open Settings and search for Font size. Adjust the slider and use the shown preview to judge the scale. Google documents Display size as a separate control for the overall interface scale.
Some apps do not use the font-size preference, so inspect the screen you are trying to improve.
Check reading and layout together
Try a message, a settings label and a longer paragraph. Decide whether text is too small or the entire interface needs scaling; those are different problems.
If only one app is affected, review its own display controls. Keep enough content visible to judge wrapping rather than looking only at a single enlarged word.
Handle model and version differences
Google notes version requirements for some accessibility controls. Search within Settings instead of assuming every manufacturer places the option in an identical menu.
For a different typeface design, consult the device maker’s supported customization options. A decorative text generator does not replace the system’s interface font.
Use the right kind of font tool
Read Unicode versus fonts before copying styled characters into a message. For real font design comparisons, explore sans-serif examples.
Keep important messages readable in ordinary text, especially when sharing with a device that may render the same characters differently.
Your questions, answered.
Does font size change every app?
Google notes that some apps do not apply the setting. Check the app you need.
Is Display size the same as Font size?
No. They control related but different aspects of the interface scale.
Can a copyable font tool change Android’s interface family?
No. It generates characters for text input rather than changing the system’s typography settings.
Sources & background
Sources supporting this page’s explanations. Practical examples are our editorial suggestions.