next.js/test/e2e/next-font/app/pages/with-fallback.js

import localFont from 'next/font/local'
import { Open_Sans } from 'next/font/google'
const openSans = Open_Sans({
  fallback: ['system-ui', 'Arial'],
  variable: '--open-sans',
  adjustFontFallback: false,
  subsets: ['latin'],
})

const myFont = localFont({
  fallback: ['system-ui', 'Arial'],
  src: '../fonts/my-font.woff2',
  adjustFontFallback: false,
  subsets: ['latin'],
})

export default function WithFonts() {
  return (
    <>
      <div id="with-fallback-fonts-classname" className={openSans.className}>
        {JSON.stringify(openSans)}
      </div>
      <div id="with-fallback-fonts-style" style={openSans.style}>
        {JSON.stringify(openSans)}
      </div>
      <div
        id="with-fallback-fonts-variable"
        style={{ fontFamily: 'var(--open-sans)' }}
        className={openSans.variable}
      >
        {JSON.stringify(openSans)}
      </div>
      <div id="with-fallback-local" className={myFont.className}>
        {JSON.stringify(myFont)}
      </div>
    </>
  )
}