Redirect 301 running domain to another running domain [SEO]

I let’s say I have landing page and (similar content & brand but different topic), these 2 are running and ranked on SERP, got traffic, but is better than in serp with specific competitive keywords (it can be on page 2-3).

The question is, when I redirect 301 to, will replace the in serp and get better ranking? (maybe jump to page 1), or something else?

Thank you.