こういう感じでしょうか。
HTML
1<div class="aaa">aaa</div>
2<div class="aaa">aaa</div>
3<div class="aaa">aaa</div>
4<div class="aaa">aaa</div>
5<div class="aaa">aaa</div>
6<div class="aaa">aaa</div>
7<div class="aaa">aaa</div>
8<div class="aaa">aaa</div>
9<div class="aaa">aaa</div>
10<div class="aaa">aaa</div>
11<div class="aaa">aaa</div>
12<div class="aaa">aaa</div>
13<div class="aaa">aaa</div>
14<div class="aaa">aaa</div>
15<div class="aaa">aaa</div>
16<div class="aaa">aaa</div>
17<div class="aaa">aaa</div>
18<div class="aaa">aaa</div>
19<div class="aaa">aaa</div>
20<div class="aaa">aaa</div>
21<div class="aaa">aaa</div>
22<div class="aaa">aaa</div>
23<div class="aaa">aaa</div>
24<div class="aaa">aaa</div>
25<button>button</button>
CSS
1.aaa {
2 display: none;
3}
JavaScript
1$( _=> {
2 $( 'button' ).on( 'click', _=> {
3 $( '.aaa:hidden:lt(3)' ).show();
4 } );
5} );
6```**動くサンプル:**[https://jsfiddle.net/L525go7z/](https://jsfiddle.net/L525go7z/)
7
8---
9
10【:hidden Selector | jQuery API Documentation】
11[https://api.jquery.com/hidden-selector/](https://api.jquery.com/hidden-selector/)
12
13【:lt() Selector | jQuery API Documentation】
14[https://api.jquery.com/lt-selector/](https://api.jquery.com/lt-selector/)