I did a little more testing, just out of curiosity. If you scale your dinosaur in its blueprints and your player pawn in its blueprints for some reason your player pawn will revert to being tiny. This can be fixed!
In your dinosaurs blueprints:
-Make an ‘Event Possessed’
-Make a ‘Get Player Pawn’, drag the ‘Return Value’ out and make a ‘Set Actor Scale 3D’
-Create a ‘Make Vector’ with your pawns desired new scale and hook that into the set scale node.
-Hook the event to the set scale node and compile!
If you need the rider to move up or down just attach a node the moves the pawns z location.
Hopefully this helps.