Yes, in some fanfictions, Tanjiro is depicted as the reincarnation of Yoriichi. This concept adds an interesting layer to the story as Yoriichi was an extremely powerful and legendary figure in the original lore. The idea allows for new storylines where Tanjiro might inherit some of Yoriichi's skills or have a deeper connection to the past events related to Yoriichi.
One implication is that Tanjiro may have access to Yoriichi's combat skills. Yoriichi was a master swordsman, so Tanjiro could potentially inherit his swordsmanship techniques, making him even more formidable in battles against demons.
One possible scenario in this fanfic could be that Naruto finds a magical sword. The sword might have special powers like being able to cut through any material or even having the ability to nullify jutsu. Naruto, being Naruto, would initially be confused about how to use it but would soon start to experiment. He might try to incorporate it into his combat style, perhaps using it in combination with his shadow clones to create some really cool and unexpected attacks.
Tanjiro might use his sense of smell to detect hidden threats. Since his sense of smell is super - enhanced, he could sniff out any demons or traps in the way of saving Rengoku. For example, if there are demons disguised as allies, Tanjiro would be able to tell by their scent.
The battle of Yoriichi vs Kokushibo can be found in the advanced stages of the Demon Slayer manga. It's an intense and highly anticipated confrontation. The build-up and action are both masterfully depicted.
He could find the sword in an ancient tomb. This tomb might be filled with traps and puzzles that Naruto has to overcome. Once he gets the sword, he discovers that it glows when near an enemy's weak point. So, he starts using this ability to his advantage in battles.