My toddler son is out of control

He literally does not give a fuck. When we’re out in public when I try to get him in the car, at home etc. he will not listen to anything. You take your eyes off him for one second and he’s drawing on the walls with lipstick or nail polish then thinks it’s funny, doesn’t care to be disciplined. Will go right back to it seconds later. Tells me no screams no at me. Hits and kicks ne if he’s doing something fun and we have to leave. Will literally physically not allow me to get him in his car seat. It looks like I’m fighting my three year old. I try gentle parenting doesn’t work I try to be more stern, doesn’t work either. He’s constantly unclipping his and his brothers car seats in the car like it’ll be a ten minute drive and he’ll do it back to back to back after I tell him no and stop to clip it back. I know there’s something you can buy on Amazon to prevent that but still… it’s the principal. I feel like I’m failing as a mom and it’s stressing me the fuck out putting strain on my marriage. I can’t take him anywhere in public or I feel embarrassed like I don’t have control over my kid. He’s also such a sweet boy at the same time. I just don’t know what to do anymore. He also hits other kids for no reason. I need help has anyone been through this ? I feel like it’s never going to change.