Where is the font size of vivo mobile phone set?

You can set it in the I theme. The setting method is as follows:

Tools/materials: VIVOX9 mobile phone

1. First, click the I theme option in your phone to open it.

2. After entering, click "My" in the lower right corner to enter the next page.

3. Then find the local font and click Enter.

4. After entering, there is a font size in the upper right corner, click Enter.

There is a slider at the bottom of the screen, which can be adjusted by moving left and right.