Time dilation is fairly common knowledge with most people knowing the greater a gravitational effect on something, the slower time appears to affect that thing to an observer less effected by said gravitational effect.
If we were to take the Big Bang/Big Crunch hypothesis and that the universe has no external gravitational effect then it’s conceivable that those two events would be momentary for the universe.
Given the Big Crunch would be the most extreme gravitational effect (drawing entirety into a singularity), time dilation would also be at its most extreme. So it’s also conceivable the beginnings of the Big Crunch have already begun (externally to those within the universe), but we are experiencing time dilation that we have to observe it occurring. If that is the case, everything within the universe has already occurred.
That is predestination. Everything that does occur, was always going to occur.