No, you don’t.
You can register a domain name without creating a website.
To make a website you’ll need to sign up with a hosting company. This is where you will store your website’s files.
Domain names are sold by domain name registrars. These are the companies licensed by ICANN (an international body that manages domain names worldwide) to register domain names.
To make a website, you need both domain name and web hosting. However, if you are not yet ready to make a website, then you can simply register a domain name.
This will give you the ownership of that domain name for the licensed period. You can make a website or start an online store later when you’re ready.