Screaming at the top of the lungs

Momma of 4

I have 4 kids and my almost 2 year old baby #3 has a new lovely habit of screaming at the top of her lungs when she doesn't get her way. Now she's my 3rd toddler so I'm very familiar with tantrums, but the problem is that she screams as if she's in a horror movie (loud and piercing) and I have a 1 month old baby (who is not a good sleeper) that she wakes up. And if I leave her in the pack n play (it's a huge pack n play not the standard size) even with a show and snack to go feed the baby to nap she'll scream bloody murder. If I take her with me to my room (no nursery because baby will eventually move in with said toddler) she will get into as much mischief as possible (she can now unlock doors and leave)

My question is I've tried ignoring her behavior so she sees it won't do her any good, but it continues. What else can I do to get her to stop (I do not spank any of my kids)