My 13 year old has high blood pressure is this normal since she did just sprain her ankle?

Transient/ persistan: It is not unusual for a kid to have a transient increase in BP readings after an injury, or during the anxiety of a dr visit (white coat htn). Close followup with a BP diary, taken in relaxed setting & after pain of injury is lessened is needed. Occasionally true treatable HTN may be discovered during an evaluation for unrelated issues so don't ignore this.

Repeat it: Any time there is an elevated blood pressure it should be rechecked at least a couple more times at different visits.