If by thigh gap you mean thinner thighs we loss weight/fat in layers. So targeting fat loss is a myth. So a good meal plan combine with a regular exercise regiment will get you the results you are looking for.
Do squats. But avoid those that bulk up the thighs and make them bigger. You cant lose weigt only in your thighs, you need to be full body active.
Go on google and read more about thigh gape and the exercises you need to do to tone them
Hope this help:)