Private DNS domain name [closed]

I am working on setting up my private DNS domain name (eg. ".sample") and hosting it on EC2 instance.

From my local machine, if I configure my DNS server to query my EC2 instance first for the DNS mapping, then I can resolve "web1.sample" to the IP address and I can access it using browser.

Now I would like to expose this "web1.sample" to the public internet, but seems like ".sample" need to be approved/registered/provided by a Internet Authority. Which I don't want to do so.

I can see another website that can have their own private domain "https://www.home.saxo/" How can I do the same as them?