Stuff like datepickers, autocompletes and whatnot are very consolidated in jQuery world. Sure there are options for vanilla JS but they are not mantained or do not have all the features.
These components are being built for the Reacts and Vues frameworks these days.
Personally I like jQuery. Like so many developers I started using it a long time ago because it solved numerous browser inconsistencies and incompatibilities. Then I got used to the clean and concise syntax. Now I use htmx more than jQuery.
You may not need jQuery because vanilla JS can do the same things now. Or you may have other tools that do what you need. But choosing something because it's new or supposedly "modern" only makes sense if the alternatives are obsolete or prevent you from doing something, and jQuery isn't either.