WhatsApp Aero is a modified version of the standard messaging app that prioritizes high-end aesthetics and deep customization

If you are searching for "install" specifically, you already know this isn't on the Google Play Store.

Customization

: Change themes, fonts, and chat bubble colors.

If you update from a previous Aero version, you can keep chats. From official WhatsApp, you need a backup.

On the same phone number, no. But you can use a parallel space app or second SIM with a different number.