Rosetta 2 is available only for Mac computers with Apple silicon.
Rosetta is not an app you open or interact with. Rosetta works in the background automatically whenever you use an app that was built specifically for Mac computers with an Intel processor. It translates the app for use with Apple silicon. Simply open your app and use it as you normally would.
In most cases, you won’t notice any difference in the performance of an app that uses Rosetta. But you should contact the app developer to inquire about a version that can natively use the full power and performance of Apple silicon.
Some universal apps (apps that don’t need Rosetta) include the setting “Open using Rosetta”. This setting enables a universal app, such as a web browser, to use plug-ins, extensions or other add-ons that do need Rosetta, because they haven’t been updated to support Apple silicon. If a universal app doesn’t recognise an add-on you’ve installed for the app, you can close the app, select this setting and try again.