The question is pretty straightforward: Is it legal to point a domain on the web to someone else's ip (website)?
The domain owner is not actually copying the content, but just opening the website in his or her own domain.
The resolution happens in the USA and the domain was bought at Google Domains
One could certainly put up a site whose only content was a link to another domain. And I can't find any law which this would violate.
If the link is a "deep link", and if it bypasses a log-in page, while the other site is so designed that all access is intended to go through the login, I believe (but cannot at the moment verify) that the owner of the other site could claim that this violates their copyright. In any case it is not a good idea.But a link to an appropriate page should have no problem, nor should pointing your domain at an appropriate entry page.
Therefor, since simply re-pointing a domain should have the same effect as simply linking, in those cases where it works at all, it should be legal. Doing it with an iframe, which would truly open another site within your site, may not be if the other site forbids such use, as in the ToS. The case law on that is not settled, but many sites object to it, as the answer by @BlueDogRanch points out.
I don't see a good reason why one would want to do this, but that isn't the question. Copying the HTML of another site and modifying the URLs while keeping the content the same would pretty clearly be a copyright infringement, besides being a lot of work to little obvious point. It also isn't what the question asked about.
Building a one-page site that has only a simple link or a redirect would clearly be legal, and would serve the purpose of causing your domain to lead a user to another site, but it isn't, strictly speaking, what was asked about either.
This will be legal except for some bizarre and very unlikely scenarios — unlikely both technically and sensically.
The only scenario when it is technically possible
Nowadays that is rarely possible: the IP address(es) that you find will either be shared with other sites, or point to an intermediary service making the site highly available and fault tolerant, or both. This requires the correct domain name to be passed with the HTTP request for it to be successful.
But once upon a time it was pretty common to setup websites in such a way that they had just one IP address associated with them (often they did not even care what domain name was used to access them, or whether it was used at all, which was making it possible to open the website in a web browser just by the IP address). This setup is nowadays rare but still existent; it is the only case where pointing another domain name is possible.
Examples of scenarios when it is illegal
Why is it legal otherwise?
Without speculating about the possible goal of pointing a domain to someone else's website address, attainability of that unspecified goal, and available alternatives, let's see what consequences may arise if someone does just what the OP says and draw conclusions from those.
So, we assume that the target can be opened by its IP address as mentioned earlier. In this case, any domain name can be pointed to that IP; upon entering the domain name in the web browser, the site will open. It won't be necessary to even register a domain to point it: one could simply edit their local hosts file.
What trouble does that create, barring the weird cases exampled above? None. No copyright infringement, no fraud, no hacking, no damage, nothing. Who's right are violated? No ones. Hence it is perfectly legal.
It doesn't work that way. Simply pointing a domain at a server IP won't do what you think, for any number of reasons, i.e., load balancing, proxies, CDNs, shared IPs, the way the webserver is configured, etc. You may be able to display a simple home page on a server with a single IP. But simply pointing the domain isn't going to rewrite the source code of the site and magically make it appear to be your domain.
You could "scrape" the site and download all content and convert the URLs to your own domain, but that requires your own server, and is typically not legal, depending on the TOS of the site you scrape; see the earlier LE question Terms and condition for web scraping
What you are probably thinking of is an iframe: HTML iframe tag. You can use an iframe to display the content of another site in a window on your own hosted domain on your own server.
But the legality of iframing a site depends on the TOS of the site you frame and appears to be in legal flux; earlier LE question Can you be accused of hotlinking/copyright violation if you use an iframe?
Many sites forbid the use of iframes as they see it - case law or not - as copyright infringement. And servers can be configured to block iframing by other hosts.
Try using an iframe for law.stackexchange.com; you'll see the error Load denied by X-Frame-Options, because Stack Exchange forbids iframing their sites, though iframing appears to not be mentioned in Stack Exchange's TOS language.
Technical details aside (you won't be able to do this; any remotely modern web server stack requires you to specify the domain names it will work with), if you do this with a website which is normally accessible via a domain name with trademark protection, serving the same content via a different domain name would be contestable in court as reverse passing off:
The action of a provider of goods or services who purchases another's goods or services, removes the latter's trademark and replaces it with its own.
This is forbidden unless you sign a so-called white label agreement, i.e. the original website owner explicitly authorizes you to set up your domain pointing to their site.