Hello wreedMH,
In general, certificates created or used in VMCA has a default validity of 1825 Days (5years), you can review the validity of the VMCA certs while navigating to vCenter Server > Configure > Advanced Settings [ and the parameter is vpxd.certmgmt.certs.daysValid ].
The Enterprise & Custom certificates can be easily extended with the help of replacing the existing certificates depending on your requirements, similarly, VMCA needs to be regenerated.