Add Google Calendar to Outlook
Firstly, sign-in to Google Calendar
Click to Options
Then, click "Setting and sharing"
Then, scroll down to the Integrated calendar, find "Secret address in iCal format" and Copy it to the clipboard.
(if you cannot see that secret address at the work account, please contact your account administrator and make sure the Calendar Sharing Setting is enabled at External sharing)
After the secret address is copied, go to Outlook.
In Outlook, click File -> Account Setting -> Account Setting
Then, you can change the name of this calendar and click OK.
When you start Outlook, it checks Google Calendar for updates and downloads any changes. If you keep Outlook open, it also periodically checks for and downloads updates.
Reference Link -> See your Google Calendar in Outlook (microsoft.com)