Quote Originally Posted by The Verge
[...] During a Microsoft Game Stack stream today, Jarret Bradley, senior gameplay producer at The Coalition, showed off how touch controls will work with Gears 5. The Coalition has built custom layouts for anything you can do in the game, including buttons for aiming, shooting, reloading, and controls for driving vehicles.

The team has even built layers where you can push buttons to bring up different views when you’re weapon changing, so the D-Pad isn’t always on-screen. The touchscreen controls even disappear automatically when a cinematic appears on-screen. The Coalition has also added gyro aim controls, allowing you to use your phone or tablet to aim a gun.

“When we first started talking about this, we were going a little over complicated because we weren’t sure what we needed to do,” explains Bradley in the talk. “As we started to dig into it, we realized the best thing for us to do is to treat this as a different input device like we already support keyboard and mouse, controller, and we have customized controls and remapping.”

The Coalition has gone back over Gears 5 and painstakingly optimized it for touch controls, but Microsoft is hoping developers will consider designing games with these controls in mind at the beginning of development. This will make it easier for developers to consider touch controls with xCloud, and for xCloud players to use them when a Bluetooth Xbox controller isn’t available.

Microsoft is now allowing existing xCloud testers to access touch controls for Hellblade: Senua’s Sacrifice today, and other games should launch with these touch controls as xCloud becomes available as part of Xbox Game Pass Ultimate in September.
This is how Xbox games are getting touch controls for xCloud - The Verge