A free mod for Final Fantasy XIV, by Astar.
If you’re looking for a shirt that will look better than the standard ones, but still be functional, then the one from FFXIV is your best bet. This mod removes the bags from the back of the shirt, so you can remove it completely if you don’t need the extra space. There’s also a mod for FFXIV that removes the belt from the front of the shirt, which can be useful if you like to have your weapons in a convenient place.
If you want to make sure that your game is up-to-date, then you can download the latest version of FFXIV TexTools, which is available for free on the GitHub repository.