Does God show a person their destiny of Heaven or Hell in this world through a sign on their body?

Marks on the body have no relation to a person's destiny in the Hereafter. No one can be attested to have entered Paradise or Hellfire unless revelation bears witness to it. Anxiety over such a mark may be caused by whisperings (waswasah), so it is advisable not to succumb to them. The fear of Hellfire should be a motive for righteous deeds accompanied by hope, so it does not lead to despair. The righteousness of a believer lies in combining fear and hope, so she should strive in obedience and uprightness.