Yes, the Xiaomi 15 Ultra supports Wi-Fi Display.
For your reference, here is more information about Wi-Fi Display:
1. Wi-Fi Display is a feature that allows you to wirelessly project or cast the screen of your smartphone or tablet to a compatible display (like a TV, monitor, or projector) over a Wi-Fi network;
2. With Wi-Fi Display, you can easily share videos, photos, presentations, or even APPs directly from your phone to a larger screen without the need for cables or physical connections;
3. This feature utilizes a stable Wi-Fi connection to ensure smooth and high-quality streaming, making it ideal for watching movies, playing games, or giving presentations.