Almost 4 y/o’s tantrums getting out of hand

I need any advice or input possible!!! Me and my boyfriend are struggling pretty bad with trying to figure out how to get through to our almost 4 year old regarding his tantrums lately. He always threw some here and there, as does any toddler, but for the last few weeks it’s gotten so much worse. Im not sure if he’s mimicking kids at daycare because he’s mentioned “well so-and-so screams at THEIR mommy” so it makes him think it’s okay for him to do? Or if he’s acting out because we are expecting our second kid in a little over a month, but I feel like since the baby isn’t here yet and the attention is still all on him then it’s a very slim chance that’s the issue??

I’ll admit I used to lose my temper pretty easily when he would act out and I’ve worked on that endlessly, my patience with him is incredible now and I try so hard to reason with him any way you can reason with a toddler. But it’s like ever since I’ve gotten better and been able to be more calm and gentle (regarding my tone), his attitude is slowly declining.

I’ve tried sitting him down and calmly talking to him about his feelings and actions, I’ve tried having him get some alone time to process his emotions and THEN talking to him, time-out, I’ve only recently taken a couple of his favorite toys and told him he has to be nice/good to get them back but I feel like that’s such a silly thing to do with a toddler. I’m just at a loss. It’s hard to “punish” or correct such a small child whose still learning how to communicate and process their own emotions. But his daycare called me and he’s screaming and hitting his teachers today, he shoved and hurt another kid in his class, he’s telling his teachers “NO” and refusing to listen. They called me and asked if there’s anything we do at home when he acts like this and I hardly even knew what to say. ☹️ I feel like I’m failing him.

My next idea when I get off work was to go to the store and get some supplies to make a “good behavior” chart and explain to him what it is. So that at the end of each day when he’s been good and has listened, he can add a star to the chart for that day or we can make a list of some activities or crafts of his choice that we can do if he was good that day (like things we don’t do daily as it is). IDK. There has to be a way to motivate him or get through to him. How have you guys dealt with a toddler acting out like this? Explaining to him that his actions aren’t ok and hurt people, or hurt peoples feelings, seems to be getting us nowhere.