I do not use to start (restart) my laptop, but I liked that sound and I miss it when a software update is done (and sure it will be switched off on mac OS updates).
Now it seems Apple has brought back the hidden option at some point with macOS Catalina. Today, Twitter user @chaysegr shared a video showing his MacBook Pro booting up with the iconic chime. He shared the terminal command that you can run to bring it back on your Mac:
sudo nvram StartupMute=%00
Type or copy and paste that command in Terminal then press return (enter your password if required). We verified that the command does indeed work on a couple of our machines here at 9to5Mac.
Shortly after, @tempaccountnull discovered that “sudo nvram StartupMute=%01” will turn it back to the default of no chime.