Office 365 (Outlook 2013/2016/2019/Web) - See Your Google Calendar
You have the ability to add your Google Calendar to your Outlook account.
By importing a snapshot of your Google calendar into Outlook, you can see it alongside other calendars in the Outlook Calendar View. To keep the imported calendar up-to-date, subscribe to the Google Calendar in Outlook. If you don’t, the only way to update it will be to import another, more current snapshot. Tip: If you don't plan to use Google Calendar anymore but want to keep your events, you can import your Google Calendar to Outlook so all of your appointments are integrated into one Outlook calendar view.
For the most up to date instructions on how to do this, please check out the following help article from Microsoft: