My toddler can be mean. How can I help change his behavior?

My toddler (3) is a sweet kid most of the time - but there are times I’m at a loss.

When he is upset, he gets pretty angry. I know tantrums are normal and I do my best to let them ride out while talking to him - I’m sorry you’re upset, I’m here for a hug, etc. Sometimes though he will hit, kick, throw something or even bite. He even hit or poor sweet dog. (We are always right there and stop immediately, reminding him that we use gentle hands and are kind to animals.)

He’s at or ahead of most milestones, very active and very silly. But his behavior in those times of anger and acting out is concerning. He’s so great at daycare but I’m starting to shy away from play dates.

Am I raising the mean kid? How do I help curb this behavior now?