<div class="search">
<input class="search__input" type="text">
<button class="search__button" type="button">Go!</buton>
</div>
<script>
[...document.querySelectorAll('.search')].forEach(block => {
block.querySelector('.search__button').addEventListener('click', () => {
window.location.href = 'https://123.ru/' + block.querySelector('.search__input').value;
});
});
</script>