My eldest dd wasn't a tantrumer. She was easy. Now 12, she's still quite easy. Bit moody, but easy. We get on well.
When my ds was 3 however? Omg how I shudder at his tantrums. One was on holiday abroad where my sister lives and it was so bad that the locals she knows still talk about it 6 years later!
He would kick off over the slightest thing. A typical monster tantrum would be.
"Mummy my legs hurt"
Me - "let's see?" (Looks at legs to see itchy dry skin)
"they look itchy. We need to put moisturiser on" (he'd had this moisturiser plenty of times before with no problem)
Ds - "no"
Me - "it would make it feel better"
Ds - "no"
Me - "ok. No moisturiser then"
Ds - "but my legs hurt"
Me - "moisturiser?"
Ds - "no"
Me - "I can't help if you won't let me. Moisturiser helps"
Ds - "no"
Me - "I can't help then"
Ds - "but my legs hurt"
........and so on and so on. Escalated into the biggest tantrum ever. The screaming, the kicking, the NOISE! Luckily we were at home. Dh eventually carried him like a fighting animal him to his room. Made sure he was safe and left him to scream it out. It took about 40 mins? Eventually he came down and ds asked if we could try a different moisturiser.
A whole evening taken up over an event that was for no real reason.
I was lucky with ds though as he had a toy lion which he adored. I would tell him that Lion would have to sleep in the cupboard as a punishment if he was really naughty (or didn't calm down within reasonable time). That used to work well for us.
I used to think I wasn't getting anywhere with ds. I would repeat the same corrections of manners, the same warnings, the same punishments over and over....until we realised one day that he just didn't kick off anymore.
He'll be 10 this year. He's so witty, popular and creative. He is different to many of his friends. He shuns sport and football, preferring sci-Fi and Lego. But the most important thing is that he great company and he is happy.
You WILL get through this OP. Yes, you may need to be firmer but it keep at it. It will change.