By default Next.js will redirect urls with trailing slashes to their counterpart without a trailing slash. For example /about/ will redirect to /about. You can configure this behavior to act the opposite way, where urls without trailing slashes are redirected to their counterparts with trailing slashes.
Open next.config.js and add the trailingSlash config:
module.exports = {
trailingSlash: true,
}
With this option set, urls like /about will redirect to /about/.