As you note in your later post, this only works once, since it forces Google to re-read the .ics URL, including all your latest calendar entries.
As far as I can tell, Outlook is actually updating the calendar at the .ics URL. You can verify this by clicking "..." next to the imported calendar in Google Calendar, then Settings, then copy the URL, then paste it into the title bar. This will download a .ics file (the same one Google Calendar should be reading). If you open that in a text editor and search for an event you added recently, you will find it, even though it isn't showing up on Google Calendar. So this is a Google problem, not a Microsoft problem.
The https://www.outlookgooglecalendarsync.com/ solution looks like it may work, but it requires running an app (continuously?) on a Windows computer. That's not an option for me with a Mac.
The discussion at https://support.google.com/calendar/thread/11953852/why-won-t-my-outlook-calendar-sync-with-google-calendar?hl=en tackles this from the Google side and has some helpful suggestions. I ended up using https://calendarbridge.com/ linked from there. This costs $4/mo but in addition to syncing Outlook -> Google, it has a calendar booking option, which lets me cancel my calendly.com account. One thing to note: Outlook doesn't publish new calendar entries immediately, although it does seem to be pretty fast. So if a new entry in your Outlook calendar doesn't show up in your Google calendar via the CalendarBridge sync, you should try right-clicking on the title of the calendar in Outlook and choosing "Sync".