Although this is not really time travel, it is a technical option.
Consider Vanitas.
He looks exactly like present day Sora, despite the fact that he exists in the past where Sora hasn't grown to that age yet. If Vanitas was able to take on the form of future Sora by Ven connecting with young Sora's heart, then shouldn't this technically be considered time travel? Vanitas has taken on the form of something that hasn't been "created" yet. I hope you'll all consider this point when making theories about the Mysterious Figure.
Consider Vanitas.
He looks exactly like present day Sora, despite the fact that he exists in the past where Sora hasn't grown to that age yet. If Vanitas was able to take on the form of future Sora by Ven connecting with young Sora's heart, then shouldn't this technically be considered time travel? Vanitas has taken on the form of something that hasn't been "created" yet. I hope you'll all consider this point when making theories about the Mysterious Figure.