This might not be a good idea and could cause problems with search engine, instead just try to focus on making the new site better by adding good stuff to it and getting more websites to mention it.
Not safe TBH
I have new sites started last year, both have 301 redirect from niche related expired domain. I didn't lose anything and in fact I am seeing slight increase in views since 03/05/2024.
you redirected expired domains, he wants to redirect his (fresh and ranking) site to something else, and in this case he will lose the rankings of the existing site. I think these are different scenarios.
that's because your actual and current site is benefiting from the authority of those expired domains, but in this guy's case he wants to 301 an already ranking site to "an old domain" (I'm not even sure that he has a site on that old domain, he didn't mention, he only said "old domain" and that's up for interpretations until he clarifies, but I didn't feel like asking for details so I gave a generic reply, still as accurate as possible, of course.)
again, different scenarios. Repurposing domain (expired I assume that you mean) for same niche is fine, but he doesn't say anything about repurposing, he only asks about 301-ing his ACTUAL site to "old domain" (which might, or might not have a site on it), and in this case he will most likely lose his ACTUAL rankings.
with the current update this is most likely true
