depending on your stroller size but you dont need to purchase baggage for it. bigger stroller will be stored in cargo hold (just tell the air crew) or if got any space in the cabin locker, those small form factor stroller can put in overhead compartment.
I bought the one that can fold into a bag size and put inside the stroller bag.

prepare some cut fruits before flight or something for baby to munch on (by right can eat some soft stuff right by now?) so that plane landing or take off give your baby to munch abit (moving the jaw might release the air pressure and to soothe your baby, sucking also can)

you need more baggage for baby stuff though haha , milk,warmer, diapers, clothes,pillow,blanket etc , nowadays my baby/kid carries more things than us parents combined

Should be enough lol, bring enough diapers else u need to shop in langkawi for it which is troublesome, milk formula if drinking powder already, if breastfeed then pump, milk packets, warmer, sterilizer(can use hot water from hotel kettle, else bring also) , bottle brush, baby pillow n blanket.

Important is diapers, what the baby eats, sleep, and something to play with to keep baby occupied in plane and during your holidays. Baby cream for any rashes and usb fan to keep cool, unless you all just hide inside aquarium or places with aircond

Enjoy the free airticket for baby and priority bassinet seating and boarding until 3 years old, after that you need to pay full price ticket for the seat hahahaa