Some have attempted to use the biblical plagues to "prove" the idea of predestination because YHWH made Pharaoh “hard-hearted - insisting that before the creation “God determined the fate of the universe throughout all of time and space.”
HOWEVER, we find something very interesting when viewing Exodus 7 through 12 through the “Hebrew mindset.” Let’s take a look:
In Exodus 7:3, we read that God will "harden" Pharaoh's heart, but did you know that the word used in the first five plagues translated as "harden" has nothing to do with hardness? Each time a plague comes and breaks Pharaoh's will, the original Hebrew as used implies God "strengthened" Pharoah's heart or that he "made Pharoah's heart heavy." It actually is a significant difference from the meaning of the English word “hardened”.
This understanding reveals it is less a situation of Pharaoh's decisions being controlled against his will; rather, with each plague Pharaoh's will was broken. YHWH then strengthened his heart (gave back to him the strength he had before the plague) and thus, Pharaoh chose defiance of his own free will. (Read carefully the 6th plague, Exodus 9:12 which specifically involves YHWH. Most English versions still use the word “hardened” and it sounds the same to the English reader. But in the Hebrew another word is used meaning “strengthen”.)
Pharaoh was thought to be a god in Egyptian theology, so YHWH was determined to show His glory over pharaoh, the elements, nature, and so on - all designed to prove that YHWH was in charge. Could pharaoh have repented? Did he have that choice? Sure, if he had renounced his crown and the spiritual claims that came with it and given his life to YHWH. But, he never did that - YHWH knew all this beforehand....
And so the plagues revealed a true tug-of-war between YHWH and man - and guess who won! Every time Pharaoh attempted to challenge YHWH, he caused his people (who blindly and apparently unbegrudgingly followed/obeyed their leader) severe grief (as is the case of many leaders today who manage to deceive people into thinking they are perfect and have the answers to everything). Cases in point can be found in the first seven of the ten plagues YHWH sent to Egypt: Blood, frogs, lice, insects, death of livestock, sores and hail (Exodus 7:1 - 8:25).