Change the number of columns and rows in a grid as the number of items increase

Question

I have to design a responsive grid.
The grid should change based on the number of items (instead of the size of the screen).

From 5 to 6 items should be 2x3,
from 7 to 9 items should be 3x3,
from 10 to 12 items should be 3x4,
from 13 to 16 items should be 4x4, and so on...

Is this something I can do using CSS Grid?

This is what I've tried:

<main>

  <figure>
    <img src="https://placekitten.com/600/400" alt="">
  </figure>

  <figure>
    <img src="https://placekitten.com/600/400" alt="">
  </figure>

  <figure>
    <img src="https://placekitten.com/600/400" alt="">
  </figure>

  <figure>
    <img src="https://placekitten.com/600/400" alt="">

  </figure>

  <figure>
    <img src="https://placekitten.com/600/400" alt="">
  </figure>

</main>

main {
  /* display: flex; */
  /* flex-wrap: wrap; */
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr));
  align-content: stretch;
  height: 100vh;
}
figure {
  margin: 0;
  /* flex-grow: 1; */
  /* flex-basis: 12rem; */
}
img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

Answer 1

There seems to be no general pure CSS solution (yet). The currently accepted answer requires anticipating the number of items, which might not be possible. A general solution exists with a little bit of scripting though, by calculating the number of columns and applying that to grid-template-columns.

As an example, in React:

function SquareGrid(props) {
  let cols = Math.ceil(Math.sqrt(props.items.length()))
  let style = {gridTemplateColumns: `repeat(${cols}, 1fr)`}
  return <div style>{props.items}</div>
}

Answer 2

Implicit columns creation can do this. You can consider nth-child()/nth-last-child() to create a new column when you reach a specific number of columns:

.container {
  display: inline-grid;
  width: 100px;
  vertical-align: top;
  border: 1px solid;
}
.container > :nth-child(2) {
  grid-column: 2;
}

.container > :nth-last-child(n + 5) ~ :nth-child(3) { 
 grid-column: 3;
}

.container > :nth-last-child(n + 10) ~ :nth-child(4) { 
 grid-column: 4;
}

.container > :nth-last-child(n + 17) ~ :nth-child(5) { 
 grid-column: 5;
}

.container > * {
  border: 1px solid red;
  aspect-ratio: 1;
}

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