If you are using the default VPC network that comes with your Google Cloud (GCP) project, and you haven't changed or added any firewall rules for that network, then you don't need to create any firewall rules. But if you create your own firewall, then you can follow the below steps.
Specify the Network in which you want to implement the firewall rule.
Specify the Priority of the rule.
Choose Ingress for Direction of traffic.
Choose to Allow for Action on a match.