Two domains for one site (Yandex and Google) Setting up in search engines?

Question

Google

That's actually the question, I've been looking for two hours now and I can't find a clear answer anywhere. I will be grateful for the answer.
1 site
2 domains link to this site, for example site.ru and site.com, everything is displayed correctly (it's all set up), now the question is about search engines, what to do next? I went to Yandex webmaster and didn’t understand what is called.
The whole problem is that one site.ru domain has already been working for about 2 years (4+ thousand pages have been indexed), now a second site.com has been added.
Question: how to make search engines perceive it as one site? Now it turns out that two domains are two different sites with the same information?

Answer 1

You need to make a redirect in .htaccess from site.com to site.ru