Does the Redmi Note 14 Pro+ 5G support Ultra definition play?

No, the Redmi Note 14 Pro+ 5G doesn't support Ultra definition play.
For your reference, here is more information about Ultra definition play:
1. Ultra definition play generally refers to the capability of smartphones to support ultra-high-definition (UHD) content, providing superior image and video quality. This is typically associated with 4K or higher resolution displays and content, as well as enhanced multimedia performance such as HDR and improved color accuracy;
2. Ultra Definition Play often refers to the ability to display 4K resolution (3840 x 2160 pixels) content. It allows you to enjoy incredibly sharp and detailed visuals; The higher pixel density provides greater clarity and detail, especially on larger screens;
3. HDR and high refresh rates provide deeper contrasts, better brightness, and smoother motion, making video streaming and gaming more immersive.