What is it called when someone asks for an opinion that almost everyone asked is going to have the same answer on?

For example, if someone said, "Who here agrees that cookies are amazing?" on a Youtube channel section for a video that is centered around baking cookies. My brain keeps jumping to the word truism, but that's for statements and is more related to whether or not a statement is factual or not.

Rhetorical Question

citation : https://www.lexico.com/en/definition/rhetorical_question

A given noun OED

What is given; the known facts, situation, etc.

As in:

The answers to his question were a given: most everyone answered the same.

A given is detail or fact that is known to be true. As in: "It's a given that I'll always love you, no matter how annoying you are."

Focusing on the asking side of your question:

I call this phenomenon Can I get an amen?. It's the act of seeking affirmation by picking the low hanging fruit of asking a question that you know will be answered positively.

How great is coffee in the morning?!?! Can I get an amen?!?!

The people who respond are often referred to as an amen corner.

Related but not exactly is preaching to the choir which is speaking as though to convert people despite knowing they already believe.

Politicians do this all the time. When they do it, it's called playing to one's base. Asking questions of this type to stoke up the audience knowing that they'll agree with the question.