How does https encrypt the response from the server before generating the symmetric key?

Question

Computer networks

How the data is encrypted when sent to the server seems to be clear:
the Server, through an open channel, sends the browser a certificate containing a public key, with which the browser encrypts data before sending it to the server.
And how is the encryption going in the opposite direction?
I know that a symmetric key is created next, but it turns out that either the browser generates it and gives it to the server as a given, or another pair of keys is needed for communication.
It is also of interest: each certificate, if viewed in Windows, has a "valid until", is this the date when the browser must check whether this certificate is still valid or the date the server must update the certificate with a key pair change?

Answer 1

the browser encrypts the data with the public key - the result is encrypted data that can only be decrypted with the private key.
those. it turns out the same thing, only the public and private keys are reversed
ps .: data encrypted with a public key cannot be decrypted using a public key.
after this date, the certificate is considered invalid and inoperative.
In the same place in Windows there is a separate section for expired keys.

Answer 2

The symmetric key is generated using the Diffie-Hellman protocol .
The date of validity of the certificate determines the validity of the certificate, if the certificate is presented before the start of the validity or after the end - it is not considered valid.