how do you guys set up dns address for a device inside a private subnet?

so, let's say you bought a domain. now you want to make the domain point to a device (let's call this device as dx). the problem here is that dx is inside a private subnet which uses NAT. so in such a case, how do we add a dns address to dx?

and are there any more complicated steps to take? like telling your ISP to give a fixed IP address to dx? what if your ISP uses Carrier Grade NAT? what if you want the domain point to a vm or a continer inside dx rather than dx itself?

The thing is guys, i am learning networking through homelabs and virtual machines. recently i bought a domain, now i need to make sure the domain points to my laptop, i looked up online and found out about whatismyip.com, but i don't know how to tell my ISP to point the domain i bought to my ip address. do i have to also tell my ISP to provide me a static ip? how do i request that?