What you could say

Simple Pastry Suggestion:
“Would you like a warm croissant or muffin with your latte today?”

Seasonal Special:
“Our caramel pumpkin latte is new this week—would you like to try one with your order?”

Size Upgrade:
“For just $1 more, I can make that a large so you have a little extra to enjoy later.”

Combo Recommendation:
“Many guests pair this smoothie with our granola bar for a complete snack. Would you like to add one?”