Is SSL not needed if using Cloudflare?

Question

cloudflare

I tried Cloudflare for the first time and noticed that the site is given over https automatically.
It turns out that I do not need to generate Lets Encrypt SSL certificates myself, for example?
Is this a complete replacement? Are these free default Cloudflare certificates normal?
What happens if I do generate my SSL on the server? Which one will work and is it configurable?

Answer 1

Not needed