Hi the Sleeper,
Thanks for your post in the Microsoft Community.
In my opinion you might use the following Power Automate template to achieve what you want.
Instead of creating an event in the SharePoint Calendar directly, we could connect the SharePoint Calendar to our Outlook Calendar first so the events will be synced on both sides.
And Once you have approve the holiday request, it will trigger the flow and create an event in your Outlook calendar. As SharePoint calendar is connected to your calendar, the event will also appear there.
Unfortunately, this community is not dedicated in the Power AutoMate, if you need further assistance of the Power Automate flow, please kindly raise a new thread in the Power Automate Community.
Appreciate for your understanding.
Regards,
Alex Chen