The registration of a domain name, hosting and developing of a website are distinct services.
You can proceed separately to the registration of your domain name before taking any other step. It is not necessary any hosting to exist already. But it is very important to find the appropriate domain name. It's not one of the things that are easily corrected when your site will already be online for some time...
Similarly, you could obtain your site's hosting. But you should be aware of the needs that will arise from its creation and operation. Any wrong choice may be not as harmful as an inappropriate domain name, but if anything, it will ultimately raise the costs you initially tried to avoid.
Although the above services are independent, they are typically managed by the website maker.