JSFiddle - React, Tailwind, and code Playground

HTML

<meta name="viewport" content="width=device-width,initial-scale=1.0">

JavaScript

function doOnOrientationChange() {  
    var viewportmeta = document.querySelector('meta[name="viewport"]');
    switch(window.orientation) 
    {  
      case -90:
      case 90:
        alert('landscape'); // Just for debug obviously
        viewportmeta.content = 'initial-scale=0.6';
        break; 
      default:
        alert('portrait'); // Just for debug obviously
        viewportmeta.content = 'initial-scale=0.8';
        break; 
    }
}

// Only bind the event on iPhone and iPad so we do not try and do this on any other device.
if (navigator.userAgent.match(/iPhone/i) || navigator.userAgent.match(/iPad/i)) {
    window.addEventListener('orientationchange', doOnOrientationChange);
    // Initial execution if needed
    doOnOrientationChange();
}