Yes you can.
You can follow the simple instructions here:
Assigning premium plan: https://support.wix.com/en/article/assigning-a-premium-plan-to-a-different-site-in-your-wix-account
Assigning a domain: https://support.wix.com/en/article/assigning-a-domain-to-your-wix-site
Of course it is better to assign the premium plan & domain to the new site only when the new site is ready for production.