I raise my voice to be heard if necessary, like when the kids are in another room or outside. I've also yelled at my kids in frustration. I'm sure most people do at some point. It is when it becomes a regular situation that there is a problem.
My stepdad was a yeller. He was NOT a hitter and he did NOT say horrible and mean things. He was simply loud and yelling all the time. He was out of control and had no grip on his own emotional state.
The more you yell, the less likely the kids will be to listen to you. If you want to be the boss, you have to be in control, and it starts with yourself. The more you yell, the less respectable you are and the more likely there is to be an environment of fear.
It took a few years after I moved out as a young adult to stop having a startle-freeze-racing heartbeat PTSD type reaction the sound of a truck's airbreak. He was a truck driver and would be gone several days at a time. When my siblings and I would hear the sound of his truck arriving home, we'd scramble to make ourselves scarce because we didn't know what his mood would be.
He realized after I left that he had a problem with yelling (still 3 kids at home) and started seeing a therapist. He changed A LOT and by the time there were grandkids on the scene, he was someone who could be trusted and relaxed around.
He did not intend to be abusive. He loved us very much. It doesn't take intention or harsh/mean words to be abusive. Volume and frequency is enough to cause trauma.
Being angry is okay, but how you handle it matters. Do what you need to do to learn how to manage your own emotional state so that you can be an effective parent instead of a reactive one.
Added: I forgot something very important - remember to apologize when you're wrong. If you slip up and yell because you've lost your cool, it good to apologise for it and amdit that you were wrong to yell. You still hold them accountable for their own behavior and they still have to follow your rules, but they need to know that you're human and fallible too. You'll teach them to take responsibility for their own wrongdoing in the future and try to make amends.