How do I open or unzip a 7z file in Windows 11?

"Run-in-Sandbox" is not a built-in Windows feature. It's a community-driven project created by Damien Van Robaeys, a Microsoft MVP. It is a context menu extension designed to work with Windows Sandbox, which is a native, lightweight, and disposable virtual machine environment built into Windows 10/11 Pro and Enterprise editions.

According to the project's documentation, "Run-in-Sandbox" has a specific feature that allows you to "Extract 7z file directly in Sandbox".

Here is the step-by-step process of how this method would work if you wanted to open a 7z file on Windows 11:

1. Installation: You would first need to download the "Run-in-Sandbox" project from GitHub and run an installation script to add its options to your right-click menu.

2. The Action: You would locate your .7z file in File Explorer, right-click on it, and select the new "Run-in-Sandbox" option to extract it.

3. The Mechanism: This action launches a clean instance of Windows Sandbox. Crucially, to perform the extraction of the .7z file within that sandbox, the tool must first have access to software that understands the 7z format.

This is the most important point: To open a 7z file on Windows 11. "Run-in-Sandbox" does not contain its own 7z extraction engine.