Here is a story retelling that critical moment from Luffy’s perspective, exploring the transition from basic instinct to the ultimate form of Observation.

Katakuri’s Observation Haki was suffocating. It wasn’t just sensing presence; it was a cold, clear window into the immediate future. Luffy felt like a chess beginner playing against a grandmaster who could see ten moves ahead.

During the fight with Katakuri, Luffy intentionally stayed in the fight to push his Observation Haki to its limit. ⚡ Comparison of Haki Levels Does Luffy have advanced observation haki? - Facebook

Luffy combines Future Sight with his Snakeman form to match Katakuri’s speed and foresight in their final clash. 📜 How He Learned It

Rayleigh taught him the basics on Rusukaina ( Episodes 516–522 ).

Luffy clenched his fist, the feeling of the hit still resonating. He grinned, wide and wild.

Luffy’s eyes widened. He gasped, leaping back to create distance.