Cloudflare sells domains at cost. If you use apple devices and pay for iCloud+ ($1.99 a month for the cheapest plan), you can get email hosting for your domain for the entire family + a catch all address.
You can run an email host yourself but it is going to cost more in time and effort to maintain than just paying for hosting. It’s not very professional if your messages go to spam due to low reputation or if you miss a message/someone gets a bounce back because the container running your mail server was down and you didn’t realize
Run mail on a custom domain for fun, to learn what it takes, but don’t do it for mail that really matters