Can a human know their destiny in this world, and is there a connection to Allah's saying: "And they encompass not a thing of His knowledge except for what He wills"?

There is no evidence for the possibility of knowing a person's ultimate destiny in the afterlife through a physical sign, and we do not know of any scholar who has asserted this. The meaning of His, the Almighty’s, saying: "And they encompass not a thing of His knowledge except for what He wills" is either that they do not encompass anything of Allah's knowledge except what He wills to inform them of, or they do not encompass anything of Allah's information in the universe except what He wills to inform them of. One must disregard illusions and whispers, and be diligent in following the Shari'a of Allah the Almighty with sincerity in one's deeds, for this is the path to Allah. It is among the beliefs of the Ahl al-Sunnah wal-Jama'ah not to definitively declare anyone for Paradise or Hellfire except with a clear textual proof from the Shari'a.