Do you mean ring longer before it goes to your networks Voicemail ?
If so then this is network driven so usually there is a short code etc in your Voicemail settings.
Check out any support pages from your network relevant to Voicemail @sandyw @
Daily Driver > Samsung Galaxy s²³ Ultra 512Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "