I've created a website in Plesk, and in my DNS records, I've added a record that resolved to the IP of the server which hosts Plesk and website.
Now I want to add that IP to the bindings of website in IIS. How can I do it through Plesk?
Plesk offers domain aliases. Domain aliases allow you to point several domain names to the same (existing) website.
Go to Websites & Domains and run the Add Domain Alias wizard.
If you don't want redirection to the main domain make sure you disable the 301 redirection.
More information can be found at: https://docs.plesk.com/en-US/onyx/customer-guide/websites-and-domains/domains-and-dns/adding-domain-aliases.65286/