<div class="search-wrapper">
  <input type="search" placeholder="Search" />
  <button class="search-btn">
    <i id="search-icon" class="fa-solid fa-magnifying-glass"></i>
  </button>
</div>

body {
  display: flex;
  align-items: center;
  justify-content: center;
  background: #fff;
  min-height: 100vh;
}
.search-wrapper {
  width: 50px;
  height: 50px;
  display: flex;
  border-radius: 4rem;
  background: #fff;
  align-items: center;
  justify-content: center;
  outline: none;
  border: 3px solid #888;
  overflow: hidden;
  transition: 400ms ease-in-out;
  position: relative;
}

.active {
  width: 350px;
}
.search-wrapper input {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  margin-left: 40px;
  margin-right: 2px;
  outline: none;
  border: none;
  font-size: 1.2rem;
  box-sizing: border-box;
}
.search-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  border-radius: 50%;
  border: 2px solid white;
  width: 50px;
  height: 50px;
  cursor: pointer;
  background: #e66610;
  margin-left: auto;
  z-index: 1;
}
.search-btn i {
  color: #fff;
  font-size: 1rem;
}

const search = document.querySelector(".search-wrapper");
const input = search.querySelector("input");

search.addEventListener("mouseenter", () => {
  if (!input.matches(":focus")) {
    search.classList.add("active");
  }
});

search.addEventListener("mouseleave", () => {
  if (!input.matches(":focus") && !input.value.trim()) {
    search.classList.remove("active");
  }
});