TipBITS: Enable the Startup Chime on New Macs – TidBITS:
When Apple disabled the startup sound by default in 2016, it was discovered that a Terminal command could bring it back:sudo nvram BootAudio=%01
Unfortunately, that approach stopped working with Mac models in 2017, presumably due to Apple removing the option in a macOS update, and since then, new Macs have started up silently. Now, however, Twitter user DylanMcD8 has discovered a new NVRAM parameter that brings back the startup sound, even on the latest Macs.sudo nvram StartupMute=%0
Also, the associated video is delightful.