According to the Sitecore XM Cloud Documentation for Developers1, you can link an environment to a specific branch of your repository in the XM Cloud Deploy app. This allows you to deploy different versions of your code to different environments.To change the linked branch for an existing environment, you need to follow these steps2:

On the navigation pane of the XM Cloud Deploy app, click Projects.

On the Projects page, click the project that contains the environment where you want to change the linked branch.

On the project page, click the environment where you want to change the linked branch.

On the environment page, click Options, then click Edit environment details.

In the Edit environment details dialog, select the desired branch from the Link to branch drop-down menu.

Click Save to confirm your changes.

2:Manage an environment in the XM Cloud Deploy app | Sitecore Documentation1:XM Cloud Documentation for Developers - Sitecore