I once planned to do a big "Six Paths Jutsu" piece but it's easier just to work on these Path by Path.
Human Path
The Human Path has the ability to interact with a human's mind and soul.
Through physical contact, the wielder can connect with the soul residing in the human body to manipulate it. Then they can forcibly drag the soul out of the target's body to kill them as they are unable to live without their soul. This is not an instantaneous process as the human body naturally resists losing its soul, and the more strong-willed opponents can push that resistance as much as possible.
However it is very difficult to actually break the caster's connection to the soul, especially as the victim grows weaker the more the soul is pulled away from them. The victim would need to attack the caster directly to force them to release their soul before it can be extracted.
But this isn't necessarily a permanent death as by preserving the body and soul in the Naraka Path, its power of restoration can be used to reconnect them and revive the individual.
The other ability of the Human Path is to delve into the psyche of the target. By resting their hand on the target's head, they can instantly separate the body and soul. The mind is the source of what makes a person who they are and thus is where the soul is most deeply connected to the body. So by channeling the Human Path's power directly into the target's brain, they can completely sever the soul from the body. Doing so causes the mind to lose all control of the body as it enters a catatonic state that lasts as long as the soul remains inside it by the wielder's will.
This vulnerability allows the wielder to then commune with the victim's psyche to experience every single thought, feeling and memory within seconds. They can bypass practically any mental defenses the victim might have and cross-examine their mind to find any information they might possess. Even if an ordinary ninja had the jutsu to read minds, they wouldn't be able to handle the strain of that much information and would take weeks, if not months, to read through a person's entire life. Those with the Human Path suffer no such drawbacks.
Once the scan is complete, they can pull the soul from the body without resistance which finally kills the victim. However these victims cannot be saved as the "wound" inflicted by the Human path causes the soul to immediately pass on to Pure Lands without hope of returning to their body.