JSFiddle - React, Tailwind, and code Playground

HTML

<p>Change language</p>
    <select id="lang-switch">
    <option value="en">English</option>
    <option value="fr">French</option>
    <option value="sp">Spanish</option>
    </select>

<p lang="en">Hello!</p>
<p lang="fr">Bojour!</p>
<p lang="sp">Hola!</p>

CSS

[lang="fr"],[lang="sp"]{display:none;}

JavaScript

$('[lang="fr"]').hide();
    $('[lang="sp"]').hide();
    let savedLang = localStorage.getItem('lang')
    if(savedLang){
      let element = document.querySelector(`option[value='${savedLang}']`);
    	element.selected = true
      selectText(savedLang);
    }

    $('#lang-switch').change(function () {
      var lang = $(this).val();
      localStorage.setItem('lang', lang);
      selectText(lang);
    })
    
    function selectText(lang){
      switch (lang) {
      case 'en': 
        $('[lang]').hide();
        $('[lang="en"]').show();
        break;
      case 'fr':
        $('[lang]').hide();
        $('[lang="fr"]').show();
        break;
      case 'sp':
        $('[lang]').hide();
        $('[lang="sp"]').show();
        break;
      default:
        $('[lang]').hide();
        $('[lang="en"]').show();
        }
    }