The SVG code examples on the Bootstrap Icons docs use 16px for width and height. This script allows to use 1em instead.

bootstrap-icons-svg-1em.js

// Use this together with this browser extension (Chrome/Edge) and enable it for https://icons.getbootstrap.com:
// https://chrome.google.com/webstore/detail/custom-javascript-for-web/ddbjnfjiigjmcpcpkmhogomapikjbjdk


/**
 * This code adds a switch checkbox on the Bootstrap Icons pages.
 * For example on: https://icons.getbootstrap.com/icons/x-lg/
 * If enabled, the SVG code will be changed to use `1em` for width and height instead of `16`(px).
 */
if (location.pathname.startsWith("/icons/")) {
  function replaceSvgPxWithEm() {
    for (const el of document.querySelectorAll(".language-html .s")) {
      if (el.innerText === '"16"') {
        el.innerText = '"1em"'
      }
    }
  }

  const fromStorage = localStorage.getItem("replaceSvgPxWithEm")
  const div = document.createElement("div")
  const input = document.createElement("input")
  const label = document.createElement("label")
  
  div.className = "form-check form-switch mt-4"
  
  input.className = "form-check-input"
  input.type = "checkbox"
  input.role = "switch"
  input.id = "replaceSvgPxWithEm-checkbox"
  input.addEventListener("change", ({target}) => {
    if (target.checked) {
      localStorage.setItem("replaceSvgPxWithEm", "true")
    }
    else {
      localStorage.removeItem("replaceSvgPxWithEm")
    }
    
    location.reload()
  })
  div.appendChild(input)
  
  label.className = "form-check-label"
  label.htmlFor = input.id
  label.innerText = "Change SVG code: replace 16px with 1em"
  div.appendChild(label)
  
  input.checked = fromStorage !== null
  
  if (input.checked) {
    replaceSvgPxWithEm()
  }
  document.querySelector("#icons-body main").prepend(div)
}