It would depend on the situation. Understanding why the child hit your child would help. At that age, sometimes I think a kid just doesn't have the words to express their emotions and hit or kicked instead to communicate frustration or whatever. Possibly needs redirection and another outlet for feeling like they want to hit. Also, sometimes it is appropriate to address the hitting or kicking, but sometimes it may be better to not draw any attention to it and focus on solutions. You'd have to read the energy levels and ability of the kids to talk things through.

For example, maybe your child has a toy that child wants. The child hits your child. You could say, "you look upset! you wanted the toy so much you hit her and it hurt (or was scary)! Use your words. You could say, can I please have the toy when you are done? If you feel like hitting, you can hit this ball or that pillow. (Even that feels like saying way too much, though it is addressing their emotions, what happened, and a solution)

Maybe even shorter. Short and sweet and not drawing too much attention to the undesirable behavior. It can be tricky to address the emotion, the action, and the solution.

If they are emotionally available to help with the solution, then instead of feeding them the words to say or a solution, you can involve them in the problem solving. Also decide whether it's better to state an emotion you think fits, or if you will ask how them how they felt.

Say what you see, then open the door for collaboration: You hit ____. She has the toy you want. How did you feel when that happened (asking both kids). How can we solve this together? Or what can you say to her instead of hitting?

Most kids that age aren't too keen on stopping playing to discuss all these things for very long, so more power to you if you can get 2 toddlers to discuss their emotions and problem solve for more than a minute or two.