Windows runs desktops apps and application files (ex: .bat, .cmd, .exe, and .msc file types) in user mode by default without elevated administrator rights unless it prompts you with UAC to run elevated (highest privileges).
When you use Run as administrator on a desktop app or application file, you are allowing it to run with full administrator access to everything on the computer. This means you are giving it special permissions to access restricted parts of the computer that would otherwise be off-limits. This could be a potential security risk if not a trusted app or application file, but sometimes “Run as administrator” is necessary for a trusted app or application file to run properly if it requires elevated rights for full access.
A .msi file is a Windows Installer package file. Is uses the Microsoft Windows Installer service to configure installer packages, such as applications.
This tutorial will show you how to add or remove the Run as administrator context menu item for .msi files for all users in Windows 10 and Windows 11.