(GCP) ERROR: (gcloud.compute.ssl-certificates.create) Could not fetch resource: - The SSL key is too large

You need to change "rsa:4096" to "rsa:2048" then ran the first command again:

                         // "4096" is changed to "2048" 
openssl req -new -newkey rsa:2048 -x509 -days 365 -nodes -out myCert.crt -keyout myKey.key

Then, ran the second command again:

gcloud compute ssl-certificates create mycert --certificate=myCert.crt --private-key=myKey.key

Finally, you can create the self-managed SSL certificate "mycert":

Created [https://www.googleapis.com/compute/v1/projects/myproject-923743/global/sslCertificates/mycert]. NAME: mycert TYPE: SELF_MANAGED CREATION_TIMESTAMP: 2022-01-22T07:22:26.058-08:00 EXPIRE_TIME: 2023-01-22T07:22:08.000-08:00 MANAGED_STATUS: