can I set my google calendar as the default calendar in Sonoma 14.0

You can add gmail calendar account from Mac calendar application Add or delete calendar accounts on Mac - Apple Support

In the last enter gmail address and its password in the next field and click done to save .

In calendar application > general , when you click on default calendar it will show the gmail address select it .

Did you look in Calendar's Settings, tab General?

I think she may be having the same problem as me. I want to go to the App Store, download Google's 'Google Calendar' application. Then the 'Google Calendar' app from Google opens instead of Apple's built-in, generic 'Calendar' app.

To be clear, I already have 'Google Calendar' app downloaded and installed. I said that in order to reiterate that I do not want to use the built-in 'Calendar' app. I want a different app altogether to be the app which is opened and interacted with.

I went to Settings > Calendar; there is nothing there to change which app is used as the default app.

I also went to Settings > Google Calendar; there is nothing there to set it as the default calendar app for the iPad.

I don't have a Google calendar so I cannot show it in this picture, but that's where you'd choose it.