Hi Poom Ritthirungrat1,
Good day.
Thank you for posting to the Microsoft Community. We are glad to assist.
Right click on the event Then Forward Then write the needed email .
This pearson will receive invitation with ICS file attached .

I hope this helps let me know if this is contrary to what you need, I would still be helpful to answer more of your questions .
Best Regards
Microsoft Community Moderator
This is not helpful. I need to be able to save the .ics file so that I can manually add an "Add to Calendar" link on meeting invitation emails. This feature should not have been removed from the new outlook. It's an incredibly important piece of my day to day business.