Every step of foot movement (water), hand movement (rowing) and breathing (breathing) should be practiced separately, and then integrated after proficiency. Otherwise, swimming hard without learning standards will naturally lead to many problems.
Also, I suggest you practice kicking your legs forward with a floating board and keep your body floating horizontally on the water for at least 500 meters. Learn butterfly stroke after mastering freestyle. If possible, it would be better to ask a coach for guidance.
Ps, when the thigh is pressed into the water, the knee joint drives the calf and thigh to press down together, and then the ankle drives the foot to pull into the water. There is a splash on the water, but not too big (a big splash means a big kick angle, which will be very laborious)