Computer Configuration > Administrative Templates > Google Chrome > Accessibility settings
Both
HKLM\Software\Policies\Google\Chrome
Enable the Live Caption feature. If this policy is set to Enabled, Live Caption will always be turned on. If this policy is set to Disabled, Live Caption will always be turned off. If you set this policy as mandatory, users cannot change or override it. If this policy is left unset, Live Caption is disabled initially but can be enabled by the user anytime.