ExpressJS - How to use custom domain on Local Machine

How do I use a custom domain (e.g: with ExpressJS? (Not Glitch) (I’m using CloudFlare for DNS)

Thank you to everyone who helped.

To clarify, are you using Glitch at all for this? You can use ExpressJS on Glitch, so it’s possible to get a domain for your Express project on Glitch by following the steps here: