Does a ionic bond form when 2 atoms share electrons?

No,a covalent bond is formed when 2 atoms share electrons.

On the other hand, an ionic bond on the other hand occurs when one atom takes/steals an electron from another atom and the resulting polarity (the differences in charges) between the two atoms causes them to attract. The atoms will have different charges since the atom that took an electron will be more negative and the atom that gave an electron will be more positive.