Final answer:
An expressive customer is likely to have enthusiastic and animated expressions, using gestures, varying facial expressions, and tones of voice that demonstrate their feelings vividly.
Step-by-step explanation:
The mannerisms a service provider can expect from an expressive customer are enthusiastic and animated expressions. Such customers tend to display their emotions openly and communicate in a way that is lively and engaging. They are likely to be effusive, use plenty of hand gestures, show a range of facial expressions, and have a fluctuating tone of voice that conveys their excitement or concerns. These attributes contrast with reserved, detailed, or calm demeanors, which are indicative of different customer communication styles.