Most parents think of children as miniature adults.
When my wife got pregnant, I asked for advice from other friends with children. One, in particular, made me think: "You have to leave your kid cry in his bed so that she learns how to behave". And I heard so many times about "Ah, I'd give you a good spank."
There are lots of specific behaviors that most people consider appropriate to children:
Anger
Yelling
Violence
The idea that children are small adults made us treat them as severely as we can't do with other adults.
This attitude comes from the mania of control.
When we see situations that hurt us, we are nervous because we can't control everything. Children are so fragile that we can use all of our "power" to "block" their weird expressions. We grow up with many expectations, and we overreact when our expectations are unattended.
Instead, it would be best if you considered this:
Your children are perfect in the way they are. Being kind and loving them is way better than having expectations.
Love your children always, over everything that YOU don't like.
When you start to look at your children not as miniature adults but as children, you will see how tender their fragility is. Children's tantrums are not a deliberate way to take advantage of you. They are candid expressions of their need to be loved more and more.
To be a better adult, consider treating children like children again.
When you have the impulse to yell to your children, to "put them back in their right place," consider how different is the height of their sight.
Squat down and get on his level, see how different they see. And discuss limits not to trespass, but love any error. Your children are growing.
Be kind to your children. You will be the pioneer of a better world.