Hey, can I have…, please. I would like…, please. What promotions do you have…, please. “I want” is seen as rude in English!

(In Australia) Person in drive through: welcome to mcdonalds. Place your order when you are ready. Person at the counter: Hi. What can I get for you? You: Hi. Can I have a big mac meal please? Person: is that a small, medium or large meal? You: large Person: ...and was that coke for the drink? You: can I get a lemonade? Person: so that's one large big mac meal with a lemonade. Can I get you anything else? You: no thanks. That's everything. Person: that will be $10. 75 In drive through: please drive to the next window. (You pull put cash or a card and they take the cash or activate the card machine.) Person at counter: here is your receipt. Your number is 163, please wait over there. You: thank you. Person: 163! (You walk to the counter and take your bag) Person: here you go. Have a nice day. You: Thank you. (Mostly these days they don't ask if you want to dine in or takeaway. The just give it to you in a paper bag and you can sit inside with it if you choose.) Another common thing you will hear these days is "your straw is in the bag." (Drinking straw)

Hello, I’d like to order..May I have..

Use the mobile app to avoid ordering anxiety & say to the lovely speaker voice: “Hi – I have a mobile order in the name of Masato?” They will say: “Masato? Got it. Pull around.” You say: “Thank you.” Easy peasy

Well usually i would say: "Let me get ..." "I'd like..." Then you can say your order, and end with "That'd be all, thank you."