Proper 301?

Hi,

I have domain A and have a domain B (which has relevant backlinks). I would like to make the SEO juice from domain B to flow to domain A but it seems that I am missing something.

My competitor has redirected his domain B to A in such a way that I can see in Ahrefs the 301 redirections, I can also see that it seems that they hosted the B domain, so I suppose they did it through .htaccess.

Will I get the same result if I 301 it through CloudFlare or directly from the registrar? Or I should also tinker with .htacess to make sure that the domain/backlink power from B is flowing to A.

Thank you for your help.