How do unread messages in short messages turn purple?

First of all, users can go to the settings of mobile phone-language and input method-font-font color and change the color to purple.

If the font color setting option cannot be found, it means that the mobile phone system does not support modifying the font color and can only use the default font color. Generally speaking, the font color of mobile phone is related to the theme used by the system, so users can change the font color of SMS to purple by modifying the theme of the system.