You can select which app you use to open a file. This is useful if you prefer to use a certain app and you want to change the app used to open a file permanently. For example, you can open all calendar files (.ics) in Microsoft Outlook instead of the default Apple Calendar app.
1. On your Mac, click the Finder icon in the Dock to open a Finder window
2. Navigate to your Downloads folder

3. Select the file, e.g., event.ics, then choose File > Get Info
You can also Control-click the file, then choose Get Info.

4. In the Info window, click the arrow next to “Open with”

5. Click the pop-up menu, then choose the Microsoft Outlook app

6. To open all files of this type with this app, click Change All…
When you open a calendar file, Microsoft Outlook is launched so you can import the event into your calendar.