adjust-viewport-width-on-narrow-device.js

const minWidth = 375
const el = document.querySelector('meta[name="viewport"]')
const updateContent = () => {
  if (window.screen.width < minWidth) {
    el.setAttribute('content', `width=${minWidth}`)
  } else {
    el.setAttribute('content', 'width=device-width')
  }
}

updateContent()

window.addEventListener('orientationchange', updateContent)