4 year old kicking dad and little brother

My newly 4 year old has been kicking her brother or pushing him down (sometimes elbows him out of the way) and he’s learning to stand up and walk. She also takes a lot of things away from him. Seldom she’ll offer toys to him. Anyways she also kicks her dad. Sitting on the stair in time out worked for a couple months but now she refuses and will crawl off the stair so it’s like I can’t hold her there and she just laughs. Even right after she kicks we tell her that hurts and she just laughs. Any tips to instill compassion and empathy?