您可以尝试minmax(min-content, max-content)

You can try minmax(min-content, max-content) ^ref

div {
  border: 1px dotted black;
}
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  grid-auto-rows: minmax(min-content, max-content);
}

.grid-3 {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-auto-rows: minmax(min-content, max-content);
}

.left {
  background-color: red;
}
 
.right {
  background-color: green;
}

<div class="grid-2">
      <div class="grid-2">
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
     </div>
     <div class="grid-3">
         <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
     </div>
</div>

您也只能使用max-content或min-content

div {
  border: 1px dotted black;
}
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  grid-auto-rows: max-content; /* min-content*/
}

.grid-3 {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-auto-rows: max-content; /* min-content*/
}

.left {
  background-color: red;
}
 
.right {
  background-color: green;
}

<div class="grid-2">
      <div class="grid-2">
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
        <div class="left">L</div>
     </div>
     <div class="grid-3">
         <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
        <div class="right">R</div>
     </div>
</div>