If you're asking how to force a win in every case, against every player, obviously you can't. Middlegame wins happen only when one player makes serious enough mistakes and the other player knows how to exploit those mistakes. No mistakes, no win. Chess is inherently a draw.
If you're asking for *general* plans for how to attack a castled king, that's a big topic, and depends partly on the opening.
Marching the h-pawn and / or g-pawn is aggrrssive and forces opponent to weaken himself. But if u are castled kingside marching pawns u might suffer aswell. A solid queen on f2 or f3 with maybe a fianchettoed bishop has proven to be a strong defense to start The attack. Both tal and fischer used to do something like this and IF u can force weaknesses while being defended u can get Nice attacks. A locked center and/or opponents piece majority on queen side is also strong. IF I iplay, say White vs french advanced his queen knight bishop can be fpcused on queen side then u can switch side. Study karpovs games. He was a master of switching from one side to another
I always met with endgame.How can I attack the castled king and win in middle game?