“All these things Jesus said to the crowds in parables… This was to fulfill what was spoken by the prophet: ‘I will open my mouth in parables…'” (Matthew 13:34-35, quoting Psalm 78:2).
“They said… ‘Let us not tear it, but cast lots for it…’ This was to fulfill the Scripture which says, ‘They divided my garments among them, and for my clothing they cast lots.'” (John 19:23-24, quoting Psalm 22:18).
The differences here are that Jesus knew full well what He must do to fulfill prophecy.
The Roman soldiers did not know they would be fulfilling prophecy.
These two examples of bible prophecy should be viewed in reference and reverence of prophecies that have not been fulfilled yet.
Only Jesus can announce when a prophecy is fulfilled.
We will not know our part.
We cannot make prophecy happen by human will.