Like a collapsible section that's lightly animated.
I worry too about people not considering accessibility.
A lot of my bugs day to day is not being able to tab into things like hover menus or being able to activate buttons because someone forgot to consider correct event callbacks.
Maybe it's different now, but using a jQuery makes it more likely the code will cover cases like that.
This isn't a complaint you can level at the gov.uk team. They're obsessed with accessibility. Gov.uk is probably the best example of a well-designed, well-built, completely accessible website on the whole internet.
There's some CSS transition stuff you can add to that to make it lightly animated: https://css-tricks.com/how-to-animate-the-details-element/
Yeah, jQuery might make some things easier, but when possible, using native HTML elements makes things even easier,
Vanilla js for similar things just looks like someone has waved the ugly stick at it.
There are sound arguments against jQuery but the "you can just use vanilla" is the least convincing.
Even GOV.UK, an incredibly lean website by today's standards, only noticed a 10% difference in their benchmarks.
Cue all the people going on about big O for parts of the code that are indistinguishable from noise in actual benchmarks.
I wish we could have standardized in the Linq-like API of jQuery.
The primary use case for it has been cross browser compatibility plus a bit of sugar. The former is _gone_ and the latter is easily replaced with a few lines of JS. Then there is an ecosystem of libraries and components around it. Many of them have ditched jQuery or have provided an API that doesn't require it.
I think if you strip out the AJAX support it can get extremely tiny.
To compare, just roughly:
For roughly the same size you can get declarative/reactive rendering with React, or an optimized FP standard library with ClojureScript, or data driven visualizations with d3 (roughly 2x the size).
For a tenth of the size you can get stuff like htmx, or a json validation library (avj), or like someone said Preact (React alternative).
But for jQuery, you're paying that for basically nothing the browser APIs don't already provide. It was a godsend 10y ago, but with legacy browsers finally fading out, the last one being ie11, you really don't _need_ it anymore.
It provides a clean API for manipulating the DOM, as this site demonstrates (which is ironic): https://youmightnotneedjquery.com/
Personally, for simple sites, I aim for vanilla JS but use jQuery (cash, actually) where it makes sense - such as working on collections of elements.