Right now, those installing the Technical Preview of Windows 10 Mobile are able to test out a new feature. This new capability allows them to remotely change an Xbox avatar from their Windows 10 Mobile powered handset. All they need to do is install the Xbox Avatar App. It is a pretty hefty file for an app, weighing in at almost 147MB.
Once installed on a Windows 10 Mobile phone, users will be able to create a new avatar for their Xbox account and even design a new look for it by changing clothes, accessories and features. They will be able to take a picture with their avatar, and save it to a new device.