Can you cheat in minecraft without a hackclient?
No how do you want to hack otherwise make no sense just for information there are also free clients
Can you download a hack that you can execute a certain command in minecraft without rights? So without a client
Nope, but that doesn't work with client either.
Do you know a command that op can give that every player can carry out?
That doesn't exist
You can't download it
There's of course no such thing would be stupid if everyone could give surgery
SUCH AS DOESN'T EXIST
And persuade the owner to give op?
There's no command that can simply give you OP rights without rights.
And ask the admin whether he gives op?
OF COURSE THAT IT IS BUT LOGICAL
But what is the best way to persuade him?
THIS IS A HUMAN AND NO MACHINE WHERE SHOULD ICJ KNOW THAT I DON'T KNOW WHAT THE PERSON IS ON IT AND WHY DO YOU WANT TO OP ON A SERVER JUST BECAUSE YOU WANT HIM OR WHAT MAN could apply and wait until he gives you the right you needs (whatever you want to do) that only takes a short time for info the questions you ask are really stupid, some of the questions you ask are LOGICALLY explainable
No, because there's no such thing.
With operating theater rights you can damage the server - so it's clear that not everyone can simply give themselves an operating theater.
Set up your own server and test it there…
It all depends on what you mean by "cheating". For example, if you want Xray (being able to look through blocks to find ores faster). Doesn't that go as far as I know without a hacking client. However, if you want to fly, for example, there are commands that you can only execute when you are in creative mode.