My horse used to bolt after jumps. Took a long time of doing down transition immediately after the jump to get him to rethink "oh I gotta slow down after jumps". Try that for a while after every single jump. Should help your horse slow down his brain a bit.
There are so many ways. You've gotta use the one that fits the situation. Find the action that would contradict the mental expectation. If it's an OTTB then you have to remember how they started life. The more claustrophobic they feel with short reins and a tight pack, the more they would fight the jockey to get there head and out of the situation. Which means a OTTB will Often start the jumping career being excitable after the jump because there is a installed anxiety that if you hold then they will fight to get ahead. Claustrophobia.
One of my most difficult lessons I had even learnt was learning how to ride a 16.3 horse OTTB on the buckle for almost a year. I was 14. But it taught me that when a horse eventually learns to not anticipate a jab in the teeth straight after the jump and instead the horse can just canter ahead after the element they start getting lazy and relaxed. Which is exactly what you want. And I learnt how to use my legs. Like I said this is one typical situation but there are many many many ways...
Come to a stop right away. And then walk off. When she stops trying to rush and listens to you and stops. Then trot off. When she gets better doing with trotting try cantering. If she rushes again go back to trotting or walking until you can canter off without her rushinh