For those looking for a direct download link, we've found a reliable source that offers TRON: Legacy in 4K HDR:

To experience the Grid in the best possible quality, use these official channels: 1. Disney+ (Best Visuals) 4K Ultra HD. Enhancements: HDR10 and Dolby Vision.

Need updates on the official release? Set a Google Alert for “Tron: Legacy 4K Blu-ray announcement”.