Can you create css-grid-like templates with a one-row flexbox layout?

Question

Can I make this structure with flexbox?

I give an example below with grid, but I want make this with flexbox.

.container {
    display: grid;
    grid-template-columns: auto auto auto;
    gap: 10px;
}
.grid-item {
    background-color: aquamarine;
}
.small {
    height: 200px;
}
.big {
    grid-row: span 10;
}

<div class="container">
    <div class="grid-item small">Cell 1</div>
    <div class="grid-item small">Cell 2</div>
    <div class="grid-item big">Cell 3</div>
    <div class="grid-item small">Cell 4</div>
    <div class="grid-item small">Cell 5</div>
    <div class="grid-item small">Cell 6</div>
    <div class="grid-item small">Cell 7</div>
    <div class="grid-item small">Cell 8</div>
    <div class="grid-item small">Cell 9</div>
    <div class="grid-item small">Cell 10</div>
    <div class="grid-item small">Cell 11</div>
    <div class="grid-item small">Cell 12</div>
</div>

What I want to achieve with flexbox:

width: 100%;
display: flex;
flex-direction: row;
flex-wrap: wrap;
justify-content: flex-start;

and

<div class="item">1</div>
<div class="item">2</div>
<div class="item big">3</div>
<div class="item">4</div>
<div class="item">5</div>
<div class="item">6</div>
<div class="item">7</div>

This is challenging because

1. is with display flex
2. in one row

Answer 1

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* debug */
body:before {
  content: '';
  inset: 0 auto 0 calc(50% - 1px);
  border-right: dashed 2px red;
  position: fixed;
}

.container {
  display: flex;
  flex-wrap: wrap;
  position: relative;
  gap: 8px;
  padding-right: calc(50% + calc(var(--gap) / 2));
  --gap: 8px;
}

.grid-item {
  width: calc(50% - calc(var(--gap) / 2));
  display: grid;
  place-items: center;
  background-color: coral;
}

.small {
  height: 200px;
}

.big {
  position: absolute;
  inset:0 0 0 calc(50% + var(--gap) / 2);
}

<div class="container">
  <div class="grid-item small">Cell 1</div>
  <div class="grid-item small">Cell 2</div>
  <div class="grid-item big">Cell 3</div>
  <div class="grid-item small">Cell 4</div>
  <div class="grid-item small">Cell 5</div>
  <div class="grid-item small">Cell 6</div>
  <div class="grid-item small">Cell 7</div>
  <div class="grid-item small">Cell 8</div>
  <div class="grid-item small">Cell 9</div>
  <div class="grid-item small">Cell 10</div>
  <div class="grid-item small">Cell 11</div>
  <div class="grid-item small">Cell 12</div>
</div>