Is there a way to increase the Siri announce calls volume?
You can change the announce notifications volume by simply asking Siri to 'speak louder', however the announce calls volume appears to be directly linked to the volume level that you have your ringer set to, not Siri's overall speaking volume so the only way to increase the volume at which Siri announces calls is to have the ringer volume set really loud which isn't ideal if you don't want your ringer loud at all other times.
You can change the announce notifications volume by simply asking Siri to 'speak louder', however the announce calls volume appears to be directly linked to the volume level that you have your ringer set to, not Siri's overall speaking volume so the only way to increase the volume at which Siri announces calls is to have the ringer volume set really loud which isn't ideal if you don't want your ringer loud at all other times.