The customisations that move the numbers: milk choice (a grande latte swings by 60–90 calories between whole milk and almond), syrup pumps (about 20 calories and 5 grams of sugar each for standard syrups), whipped cream (roughly 70–80 calories on a grande), and size. Those four account for nearly all of the variation between two versions of the 'same' drink.
The ones that do not: an extra shot of espresso adds about 5 calories, temperature requests change nothing, and 'light ice' changes the coffee-to-milk ratio only slightly. Half-caf and decaf change caffeine, not calories.
Knowing which levers are real makes ordering calmer. You stop negotiating with the whole menu and just adjust the two or three things that matter for the drink in front of you.