Infinity War in Blu-ray 720p quality, you can consider purchasing the digital version of the movie from online platforms such as Amazon, Google Play, or iTunes. Once you have purchased the movie, you can download it to your device in 720p quality. Keep in mind that the file size may be large, so make sure you have enough storage space on your device.
Alternatively, you can rent or buy a physical Blu-ray disc of the movie and use a software program to rip the disc and convert it to a digital file in 720p quality. This process can be more complex and may require some technical expertise. Some popular software programs for ripping and converting Blu-ray discs include Handbrake, MakeMKV, and AnyDVD HD. However, it's important to note that ripping and converting copyrighted material may be illegal in some jurisdictions, so it's important to make sure you have the necessary permissions before proceeding. Additionally, the quality of the ripped and converted file may not be as high as the original Blu-ray disc, so it's always recommended to purchase or rent the movie legally if possible.