Why though? Seriously. Is this one of those "ban things that i don't like" things?
If you have suicide related trauma triggered by or related to isekai/reincarnation, you could read the descriptions more closely and look at comments before reading. particularly of the early chapters. I do that even without having any trauma that can be triggered by manga. I do support a suicide tag though. If we had that, you could just blacklist suicide, but as for now, your best bet is to blacklist isekai or reincarnation. If you're "looking out for the impressionable youth", i hope that the fact that someone looking to commit die in order to get isekai'd probably didn't have much time left to begin with eases your mind.