There does not seem to be any built-in facility to enable a user to create a Task from an Event in Google Calendar.
There are a couple of external options available from Zapier and Microsoft. At the moment I’m trying out “Create a Task in Google Tasks when a Google Calendar Event starts”, available within Microsoft Power Automate but MPA is powerful business software and far too complex for my requirements.
Is there a more simplistic solution?
I sometimes write stuff on the back of my hand as a reminder.
I want to exclude human intervention … 
Where does the initial input start from then ?
My Google Events are mainly manually entered - at that stage I am able to integrate automatic email notifications and screen prompts. However, once those have been issued (days, hours, minutes before due date/time) then there is no further “reminder” to action an event, if required. Given the complexity of modern life and my failing memory, I may well miss an actionable event (like paying off a credit card in time) so I want that action posted as a task that will not disappear until I have marked it as completed.
So, it’s the manual intervention between event and task, like that between event and prompt, that I want to exclude.
I get email reminders from google calendar a day or two before the event, I leave the email unread and up near the top of the list there continuing to remind me.
I also email myself reminders of things that may or may not be on the calendar.
I do that, too … emails plus screen notifications but emails get lost in the crowd and notifications get dismissed … 
That, for me, would be another function of Tasks or Google Keep.
It is, of course, very easy to create a Task from an email - just a click away. I expected that something similar would be available for Events.
cut it up
If your using android you could add an alarm for each event in the Clock app. Thats what I do so every week I get a reminder at 7pm on a Monday to put the bins out and every Thursday and Friday at 15:45 to unlock the door for Charlie when he gets home from school.
You can also schedule calendar events this way too.
I generally use the calendar with timed reminders before the “event”. It comes up on my screen and I have the option to dismiss it or not. If not, then it stays there until completed. Otherwise I just use a notebook as a back up.
I just have a large ‘year planner’ on the wall in the hall. At least it still functions when the internet is down or we have a power cut!
Well said Tabby, we need to stop encouraging the “Bots” 
Having spent some time assessing the Zapier and MS offerings, I have come to the conclusion that both, in their complexity and performance, are ideal for a working environment but far too demanding for a domestic context. A professional user would, no doubt, be offered courses on how to integrate the products into an organisation.
The alternative seems to be to make better use of Google Tasks, which I already use as a “notepad” and “to-do list” but which has been significantly enhanced since I last assessed it.
https://automate.io/blog/google-tasks-app-guide/
What is Google Tasks?
Google Tasks is a simple to-do list from Google that was launched way back in 2008. Back in those days, this app was literally overshadowed by Google’s other primary features.
There was no direct way to access GTasks from either Gmail or Google Calendars up until 2018 when Google made several design changes and placed Google Tasks icon on the right-hand panel across all G-Suite apps.
GTasks offers you everything you are looking for to create an effective to-do list. It has the most minimalistic design layout giving it a feel of using pen-and-paper, but with added benefits. There is nothing complicated about this Google’s to-do list app, nor is it designed to handle complicated work projects. For that, you have advanced task management apps.
7 Powerful Features in Google Tasks Start Using
- Add Tasks, Sub-Tasks and Recurring Tasks
- Add reminder to Google Tasks (or import from Google Reminders)
- Create multiple Google Tasks lists for different projects
- Add Tasks to Google Calendar (and vice-versa)
- Add Google Tasks from Gmail in one-click
- Hide completed tasks on Google Tasks
- Create tasks on the go with Google Tasks’ Chrome Extension
I shall convert a few “Events” to “Tasks” and evaluate the results.
So far, so good.
I’ve discovered the hidden “Shortcuts” menu but the “Sub-tasks” function doesn’t work (apparently withdrawn by Google).
However, there is a Chrome plug-in to make entry full-screen and this seems to still have the “Sub-task” function.
ETA Google Tasks won’t accept the sub-tasks created by Full Screen - ATM, for me, sub-tasks are not essential, though.
sub-tasks: making the bed, washing up, reading the metres …
tasks-proper: serving G&T’s in the garden, serving dinner on time, chauffeuring her majesty with a smile …
Please tell me you don’t need google to remind you about any of those! 
