If you are designing a Mushaf, a website, or a mobile app, here are the industry-standard fonts. Note: Some are proprietary; others are open-source.
The field is evolving. Two major trends are shaping the next generation of Arabic fonts for the Quran:
Modern digital Qurans color-code the tajweed rules (e.g., red for Ghunna, blue for Idgham). If you use a standard font, it won't have slots for these colors. You need a font with "Color Glyph" support or use layered text.
Before downloading, it is important to understand the two major categories of Quranic fonts:
Standard fonts are black only. If you are creating educational materials, you need Tajweed Fonts.
Developed by SIL International (famous for Gentium), Scheherazade New is a free, open-source font that supports the full Quranic Unicode range.
You cannot usually change system fonts easily, but you can use specific apps: