what’s something rich people do that instantly changes the atmosphere in a room?

not talking about obvious flexing.

i mean subtle things that immediately tell you someone’s operating on a different level.

In a speaker setup.
High iq is the most obvious thing. Knowledge about the subject/topic they are speaking about.
Here is an example:

Since you said obvious flexing here is an example of obvious flexing, I worked for this guy for 4 years, not a random example:

baby oils

Usually they dont try to impress anybody
They speak slower stay calm and never look desperate for attention
Biggest difference is they make other people relax instead of trying to dominate the room

look like boss in the room

Less anxious
Wearing a little smile
The "I dont care attitude"
Holding attention

Boosy walk and a confident speech, whether it's a long speech or a short speech

Most truly ultra-rich people don't want to show it and try to hide it instead, you've been fooled by Instagram fake gurus. Ultra-rich people have nothing to sell you directly, so they won't try to prove a point.

Old rich vs. new rich.

Generational or old rich try to blend in. There's no value to them in showing off or proving their wealth. They have it, are comfortable with it and gain more by blending in than showing off.

New rich (think social media influencers, Bezos, Elon) feel like they need to show off their wealth to get people to envy, admire and win popularity. They don't realize that their wealth is a target and long-term actually puts them in greater danger than if they were to just blend in.

The richest guy in the room is the guy who drives in a Toyota sedan and showed up wearing a t-shirt and jeans and a $100 pair of sneakers. And the only tip-off of his wealth is the $125K vintage Patek watch he's subtly wearing, that most people wouldn't notice.