When dieting, should I look at the portion size rather than the calories when eating out?

When I eat out, it is difficult to know the exact calorie count of each menu item, so I struggle to decide what criteria to use when making a choice.

Even with the same menu, I think there will be a big difference depending on the amount of rice, sauce, and side dishes.

I'm wondering if it's better to look at the types of food first or adjust the overall quantity in situations where it's difficult to calculate the numbers individually.

For those who dine out frequently, what criteria do you check first when choosing a menu?