It varies carrier by carrier depending on their agreement with ESPN. I believe Xfinity is a no, Directv is a yes at this time. I'd start by searching "[cable provider] espn direct to consumer" in Google
I have Youtube TV, which does not have an agreement yet with ESPN. I tested the app out, and I still watch channels that are part of my package with my authentication. I'm only blacked out of things designated as part of "ESPN unlimited" (I separately have a subscription to ESPN+, so I get that stuff but not from my TV provider). As far as I can tell, ESPN Unlimited is currently just a handful of preseason NFL games and WWE pay-per-view shows. My understanding is that MLB TV would fall under this ESPN Unlimited category, but that hasn't been made official yet