You can adjust the font size by doing the following:
iOS
- Go to Settings > Accessibility, then select Display & Text Size.
- Tap Larger Text for larger font options.
- Drag the slider to select the font size you want.
- Then you can go to the app and the texts will be already enlarged
Android
- Open your device's Settings app.
- Select Accessibility Text and display.
- Select Font size.
- Use the slider to choose your font size.