<div class="container">
  <div class="block">t1</div>
  <div class="block block2">t2</div>
  <div class="block block3">t3</div>
  </div>

* {
  box-sizing: border-box;
}

.container {
  width:100%;
  background:#eee;
  max-width:1000px;
  margin: 0 auto;
  display:flex;
  flex-wrap:wrap;
  gap:30px;
  
}

.block {
  heigth:500px;
  flex: 1 1 50%;
  background: green;
  max-width:50%;
}

.block2 {
  background: yellow;
}

.block3 {
  background:blue;
}