How do u make it tighter?

Ladies i would like some advice, I've had one baby about a year ago and my partner sometimes says during intercoufse that my vagina isn't as tight anymore which is understandable as I pushed a baby out of it, but I am having another baby and I am worried that my vagina will never be a comfortable tightness to pleasure my partner during sex again.. once you had your first second three child etc, what did u do ? I know there's pelvic floor exercises but do they really work?