"Ojou is a formal Japanese word for literally "young lady", is typically used in anime when referring to wealthy, high-class female characters. Most Ojou characters can be boiled down to three main types: a Proper Lady, an Ice Queen and Royal Brat version. The key point is that other people treat her like royalty, whether or not she actually is. For Ice Queen and Royal Brat types, their iconic action is called Noblewoman's Laugh."

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"Noblewoman's Laugh is a stereotyped laugh used by women from aristocratic Japanese or pseudo-Japanese families, usually written "ホホホ" or "ほほほ" (ho ho ho), or sometimes "お~~ほほほ" (o~hohoho) representing a high-pitched, somewhat artificial form of refined feminine laughter (rather than the belly-laugh that "ho ho ho" represents in English. Typically associated with the Ojou character type, or haughty, stuck-up women. These characters are most likely to exhibit this laugh in moments of arrogance or when contemplating how they'll humiliate their enemies. They frequently will pose holding a straightened palm vertically to the side of or below their mouth, or holding a fan over their mouths. This comes from the custom that refined Japanese women don't expose their mouths while laughing".

There's an entire YouTube channel dedicated to this trope.
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Fun fact for myself: This is currently my favorite trope. I find these characters to be so funny and enduring, well some of them anyways. Tis all