It likely has to do with moisture....too much or a lack thereof. Droop like this is either from overwatering or it just needed water in that big ass container. It looks like you just gave some water so give it time..
Try watering more often but with a hand mister to keep soil moist without drenching it. Next time go with a smaller pot to start off with. If the soil was bagged you probably don’t need to ph adjust the water either...what kind of mix do you use?