Terrible Two’s Discipline

Hey moms I’m having some problems on how to discipline my toddler, he never before had meltdowns with me or hubby but with my mom and dad he does, well now he’s realize that meltdowns and tantrums gets him what he wants. It’s getting harder to go out and sometimes I get so frustrated at stores and restaurants and just leave bcus it seems like he gets louder and all those judging eyes staring at me. I’m expecting #2 and idk how I’m going to not loose my mind, Any advice and or recommendations And is anyone else suffering like I am 😩