The Imams عليه السلام do have the knowledge of what was and will be, and that nothing is unknown to them عليه السلام

6. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from ‘Umar ibn ‘Abd al-‘Aziz from Muhammad ibn al-Fudayl from abu Hamzah who has that he heard abu Ja‘far عليه السلام say the following. “No, I swear by Allah, the scholar (who possesses Divine authority) is never ignorant or knowledgeable in something and ignorant of other things. The Imam عليه السلام then said, “Allah, the Most Holy, Most High and Most Gracious, is far exalted and above imposing the obedience of a servant (of His) on the others and then hide the knowledge of things in the heavens and on earth from him and then say, “Do not hide that from him.”