Yes, you can create a multi column list as described if you make the ul a flex container, change the flex-direction to column, allow it to wrap by applying flex-wrap: wrap and additionally force it to wrap by limiting its height:
ul {
height: 100px;
display: flex;
flex-direction: column;
flex-wrap: wrap;
}<ul>
<li>item 1</li>
<li>item 2</li>
<li>item 3</li>
<li>item 4</li>
<li>item 5</li>
<li>item 6</li>
<li>item 7</li>
<li>item 8</li>
<li>item 9</li>
<li>item 10</li>
<li>item 11</li>
<li>item 12</li>
<li>item 13</li>
<li>item 14</li>
<li>item 15</li>
<li>item 16</li>
<li>item 17</li>
<li>item 18 </li>
<li>item 19</li>
<li>item 20</li>
<li>item 21</li>
</ul>Here’s another possibility, added half a year later after the comment by @Andrew Koper:
You can also use the colummn-count parameter, which doesn’t require a fixed height (and also not flex), but defines a fixed number of columns. So in the example below, even just two list items would be broken into two columns of one list item each:
ul {
column-count: 2;
}<ul>
<li>item 1</li>
<li>item 2</li>
<li>item 3</li>
<li>item 4</li>
<li>item 5</li>
<li>item 6</li>
<li>item 7</li>
<li>item 8</li>
<li>item 9</li>
<li>item 10</li>
<li>item 11</li>
<li>item 12</li>
<li>item 13</li>
<li>item 14</li>
<li>item 15</li>
<li>item 16</li>
<li>item 17</li>
<li>item 18 </li>
<li>item 19</li>
<li>item 20</li>
<li>item 21</li>
</ul>