He sends his previous attacks beat him, to get Sentomaru in a position to beat, all the previous shots pushed Sento in a place where he will get hit.
Kizaru needed multiple shots to beat Sento. Dodging or blocking or taking the attack is irrelavant.
How do you know Sento didn't get internal damage while trying to block Kizaru's kick?
Blocking those attacks also drains Sento's stamina, and Haki as well, since Sento was already damaged before the fight too. Previous attacks pushed Sento into a corner where he could finally get hit.
Kizaru didn't one shot Sento, he needed to make him tired with previous shots to get there.
@ZenZu