【Xbox Series X|S/Xbox One/ Like a Dragon: Infinite Wealth】 Are there any items or completion elements that aren't available without using the Internet?

By playing the online elements, you can earn "Miles" that can be used to obtain "Titles," "Avatars," and other items that can be set when uploading your own data.
*Please note that these elements are not required for completing the game or achieving trophies. Therefore, they don't affect completion if you choose not to play with them.