Overview
Command 'git' do not allow you to create repo but it's possible to create new repo at github from BASH script. All solutions use user/password authentication which is deplicated but stil in use. Authentication must be done using personal access token.
Below there are solutions:
3rd party application
https://github.com/github/hub
sudo apt install hub;
cd <folder with code>;
hub init;
hub create -p -d "<repo description>" -h "<project site>" \
"user_name>/<repo_name>";
More options: https://hub.github.com/hub-create.1.html
Pure BASH
REPONAME="TEST";
DOMAIN="www.example.com";
DESCRIPTION="Repo Description";
GITHUB_USER="github_user";
FOLDER="$HOME/temp/$REPONAME";
mkdir -p "$FOLDER"; cd "$FOLDER";
read -r -d '' JSON_TEMPLATE << EOF
{
  "name" : "%s",
  "description" : "%s",
  "homepage" : "%s",
  "visibility" : "private",
  "private" : true,
  "has_issues" : false,
  "has_downloads" : false,
  "has_wiki" : false,
  "has_projects" : false
}
EOF
JSON_OUTPUT=$(printf "$JSON_TEMPLATE" "$REPO_NAME" \
  "$DESCRIPTION" "http://$DOMAIN");
# https://developer.github.com/v3/repos/#create-an-organization-repository
curl -u ${GITHUB_USER} https://api.github.com/user/repos \
  -d "$JSON_OUTPUT"