Luffy got the scar on his chest during the battle of Marineford which is also known as the Paramount War. This was a major conflict where Luffy and his allies fought to rescue his brother named Ace.
During the intense battle, Luffy faced many powerful enemies. The scar was inflicted by Admiral Akainu, who used his devastating magma powers to attack Luffy and the attack left a large, X-shapped scar on Luffy’s chest.
This scar is a reminder of the sacrifices and struggles Luffy went through to save his brother and marks a significant event in his journey as a pirate. The battle at Marineford was a turning point in Luffy’s life, shaping him into the determined and resilient leader what he today is!