hello
If using custom certs , signed by external CA along with root and intermediate key .
Validity of those certs if 90 days , 180 days or xxx days .
It can't be renewed from vmware certificate manager , only thing you can do is add new custom certs to vcenter stores such as machine_ssl_cert.
All the custom certs can only be replaced and self signed only can be regenerated

https://kb.vmware.com/s/article/2097936
Regards
Harry