How to simulate a large flow of visitors to the site / web application?

Question

stress testing

Suppose there is a site that is being developed for high loads, traffic is about ~ 100 thousand people per day, 15-20 thousand online.
What are some ways to test the endurance of the servers and the actual response speed of the site under load? Is it possible to conduct aggressive testing to find out at what number of users the server crashes?
Also interested in the ability to program the real behavior of the user, and not multiple access to the same URL'u?

Answer 1

https://tech.yandex.ru/tank/

Answer 2

Habraeffect?