[{"data":"Physics"},{"data":"11th-Physics"},{"data":"JEE-IIT-Physics"},{"data":"Physics-Physics"},{"data":"Something Unrelated"}]

db.collection.aggregate([{"$match":{"data":{"$regex":"Physics","$options":"i"}}},{"$addFields":{"score":{"$indexOfCP":[{"$toLower":"$data"},{"$toLower":"Physics"}]}}},{"$sort":{"score":1}}])