Does creating backlinks to a url that redirects matter?

I'm learning SEO using a friend's business page. We are looking to get him to rank locally with google business, but there are two domains. 10 years ago someone made him a website, few years later the webmaster dipped and he had lost control over his domain which he then had to make a new one adding his industry at the end of the domain.

ex: Llamalovers was the old site and now llamaloversreservation became the new

Eventually the old domain expired and went for sale, he bought it and had that old domain redirect to his new one as his current customers are now familiar with this one. He lost the info and has to contact his website admin to transfer over the info so I can edit the whole theme as well as do some on page optimization.

Should I be doing seo for llamalovers.com as it will be the main domain? This domain is 11 years old vs the newer domain (6 years old.)

What will happen to newer domain's backlinks once llamalovers becomes the main domain? Does it even matter as it will redirect to the old domain once I get the logins? Current domain doesn't have much backlinks but for learning purposes I'd like to know

Hi There

age of domain is not the major factor in SEO anymore. If i were u, I would focus on the present website (6 years) old totally. As you have control over the older domain (11 years old), I would create a blogging platform and use to post the quality content there as well.

That way you have two birds to play around with.

Good luck.. Need help, feel free to touch base.