Hi there,
I'm Cherrelyn and I'm here to help.
I'm sorry to tell but the consumer version of Teams doesn’t have the “Test Call” feature built in like the work/school edition. If you want to check your mic, camera, and audio, the closest workaround is starting a call with yourself by creating a private meeting in your calendar and joining from another device or account. You could also make a quick test call to a friend or family member just to check your setup before any important meeting.
I hope this will help and If you have any question please feel free to ask.
Warm regards,
Cherrelyn