I don't know of official documentation for this, but I believe the link format should be as follows:
https://outlook.office.com/calendar/0/deeplink/compose?body=description&enddt=2022-04-01T13%3A30%3A00%2B00%3A00&location=location&path=%2Fcalendar%2Faction%2Fcompose&rru=addevent&startdt=2022-04-01T13%3A00%3A00%2B00%3A00&subject=title
or to make that a bit more readable:
https://outlook.office.com/calendar/0/deeplink/compose
?body=description
&enddt=2022-04-01T13%3A30%3A00%2B00%3A00
&location=location
&path=%2Fcalendar%2Faction%2Fcompose
&rru=addevent
&startdt=2022-04-01T13%3A00%3A00%2B00%3A00
&subject=title
The date times above are URL Encoded so before encoding would look like:
2022-04-01T13:30:00+00:00
Should be self-explanatory (yyyy-mm-ddThh:mm:ss+zz:zz) the last bit after the + is the time offset from UTC (hh:mm) of the timezone.
Source:
https://www.labnol.org/apps/calendar.html