Training to self soothe

We are just starting the 4 month sleep regression and I think we may need to sleep train or it’s not sustainable. Baby doesn’t seem to have trouble falling asleep independently. At bedtime (7 pm) we do our routine and put him down in the crib awake, and as long as we aren’t early or late then he can fall asleep alone without issue. His daytime schedule is approx 1.25/1.5/1.5/1.5/2 and his dwt is 7 am. The problem is he has been waking up every 30min to an hour screaming his head off. Once he’s calm again, even if he’s wide awake, he can manage to fall back asleep alone. What should we do to train him to stop waking up screaming? I’ve tried waiting it out a bit but usually the screaming intensifies until I go and soothe him. Is it really just a matter of continuing to ignore his cries? I feel it gets increasingly hard to do later in the night as I get more and more tired and agitated. Help us please!