Hi and thanks for the questions. I will use the word prune/pruning instead of break, and leader/trunk instead of crown, but I think I understand your questions. Breaking the crown of the plant, to me, means breaking the trunk off at or near ground level. This is not recommended.

Can the height of bristlecone pine be controlled through pruning? Yes, although this will be an ongoing process, not a one time event. Will the plant grow out more than up if pruned? That is hard to predict. Generally, yes but to what extent? Also, the practice of topping and pruning trees for height control is generally not recommended as a long term solution. If you do prune to control height, make pruning cuts above a lateral branch, or selectively remove the tallest leader/trunk and leave shorter trunks if the plant has more than one trunk/leader.  A better long term solution is to choose a plant that grows to the desired mature height.

Thank you,
Chris 

Chris Hilgert
Colorado State University Horticulture Statewide Specialist