How to Create Events Calendar

How onthisday.com has been made? I'd want to make something similar.

I guess I need to have a database with some events happened in a day (6 february 2021, 6 february 2020, 6 february 2019 ... 6 february 2014) and then I want to show all the events happened on that day.

I have no idea on how to start and I'll appreciate any help. Thanks