The latest episode sees Luffy reach a new achievement in his Haki use as he, just for a moment, manages to see into the future much like Katakuri has been doing this entire time.
In Episode 864 of the series, the fight has resumed with Katakuri. Luffy's still struggling against Katakuri, but remembers when Katakuri said he had to be calm in order to use his Observation Haki. This was after Luffy broke up his Merienda, and caught him by surprise. His frustration meant he was no longer looking into the future, and Luffy was finally able to hit him.
Taking this to heart, Luffy tries to calm himself for a moment. In this brief time, he manages to see Katakuri forming a minigun and firing mochi. He manages to dodge this first volley, but then is overwhelmed by subsequent attacks. After this works, Luffy mentions that he managed to see some of the future.
Now that Luffy has figured out the trick, that he has to be calm, it's more of a matter of putting it into practice. By the looks of the preview for the next episode of the series, Luffy is able to use this ability even more so after he figures it out here.
Luffy's inner strength lies in how he manages to adapt his abilities depending on the foe he faces, and thus he's evolved even further than he has ever had thanks to battling a strong opponent like Katakuri. It's why Luffy is such a dangerous element, and even when things go badly for the Straw Hats, enemies should not count him out until the end.
Eiichiro Oda's One Piece first began serialization in Shueisha's Weekly Shonen Jump in 1997. It has since been collected into over 80 volumes, and has been a critical and commercial success worldwide with many of the volumes breaking printing records in Japan. The manga has even set a Guinness World Record for the most copies published for the same comic book by a single author, and is the best-selling manga series worldwide with over 430 million copies sold. The series still ranked number one in manga sales in 2018, which surprised fans of major new entries.