I can't get out of my mind how hard it's going to be having a young child and new baby. Like how…

I can't get out of my mind how hard it's going to be having a young child and new baby. Like how does a grocery store run go? You have to carry the car seat and hold the toddler hand? Or do you just carry baby in carrier (that's seems easier, free both hands)? Having a stroller is out of the question because you can't push stroller and cart together.