DNS migration

When doing DNS work to repoint a subdomain to Cloudflare would it be better to

  1. Create a CNAME
  2. Change the subdomain record into an NS record and specify cloudflare’s name servers as the value?

Please also share the pros and cons or what is the official best practice from Cloudflare.

Unless you have a Business or Enterprise plan, the entire domain has to be on Cloudflare. You can’t CNAME or delegate a subdomain into Cloudlfare on Free or Pro plans.