IPHONE 13 PRO MAX BATTERY DRAINING FAST THAN EXPECTED

hello,

three days ago i just bought my new iphone 13 PRO MAX online (saudi arabia), upon 6% battery i charged my phone using the magsafe for the first 30mins it was already 46% but the back of my iphone is hot so i shifted my charger to the original i use for my ipad 8th generation. then it was charging so i turned it off thinking it will charge well when turned off. but it took a total of 4 hours to charge for my initial charging. but i was thinking maybe it is because it is new and the initial charging might really take long especially it is a PRO MAX. then for the first 2 days i notice the battery to be draining faster than expected (through after reading and watching vlogs, saying continuous usage may take upto 10 hours- while video streaming takes 20hours) unfortunately mine takes only 7-8 hours with only 4-5 hours of continuous use and it was quite hot especially when im outdoor with no aircon, but i thought it might be because of the transferring from my old iphone to the new iphone 13 pro max. so i charged it again using my ipad charger and when it was full i removed my magsafe iphone 13 promax case thinking it was the reason my phone was heating when used and when charging. now is the third day of my new iphone, i am not satisfied with how the battery is draining (even when im not using the phone and it is not connected to wifi it is still draining which is very unusual especially that it is supposed to be a PRO MAX with abetter battery life that is why i bought it in the first place) . :( :( :(

Can anyone enlighten me if this is normal or is the battery is really defective? i was planning to return it to the store and have them replace it with a new one since it is still covered in the return exchange policy? many thanks

-lil