Today we gonna teach you how to crash a server without op means you can destroy your friend's server and bully him lol

Survival mode:
If you are in survival mode in the server sadly there is no instant crash for the server, you have to build huge machine which will contain like 10k piston pushing 10k armorstand up, which Is a lag machine!

Creative mode:
If you somehow got creative mode in the server means you have op!
You can get op with only being creative mode so
/gamemode creative Amir = /op Amir
But I am not gonna teach you how to get op in creative mode
Probably in another post
But in this test you can crash the server using only an item
Named virus!!!
How to get it?
Just add a lot of nbt tags to an item then it will be a virus!
If you put It in your saved hotbar then go into the server and put the item from the saved hotbar into your hotbar the server will get destroyed (but if the server has a lot of ram and space you should add a little bit more nbt tags)
Sadly this won't work on any server, cause some plugins like banitem will not allow it

I know this wasn't a helpful post but I tried my best