In general, if you reply to a message, no matter where it came from, it will use the address it was sent to as the reply address. The exception is if you are a member of a group / distribution list - those responses will come from you personally.
Here are several articles on how to change the "from" address for new messages:
- Using the From field in Outlook to send from an Alias, Shared Mailbox, or as a Delegate
- Accessing a Shared/Delegated Mailbox from Microsoft Outlook Desktop App
- Send email from a different address in Outlook on the web
- Google Workspace: Send emails from a different address or alias
- Accessing a Google Workspace Shared Delegated Inbox on your Mobile Device