Digital signing of SSL certificates?

Question

Digital certificates

Let's say there is a purchased certificate or a certificate from Let's Encrypt. If we take the certificate of the root certification authority from these certificates and use OpenSSL to sign the certificate with it, will it be recognized by browsers and email clients or not?!
Tell me please!

Answer 1

> to sign a certificate with a
public key, you do not sign a certificate, but a private one - only with the owner of the root CA.

Answer 2

Think logically. Signing requires a private key. You don't have it if CA is not yours.

Answer 3

Danya, I like your way of thinking :)
But it's still worth reading about public key cryptography and the process of issuing certificates :)
Issuing a certificate is the formation of a new certificate file based on the information that is in the certificate request file. To do this, you need to have two files - a certificate and a certificate key. Everyone has a CA certificate. The CA key is not held by anyone other than the owner of the CA.
Accordingly, you cannot issue a certificate :)