Not sure if you'd die, but it would hurt like hell. I have leftover meds from changes, and the ones I'm on now, which tends to concern my providers. Lithium in particular, any provider I've spoken to who knows about my chronic suicidality has been concerned about me having access to that. Initially they'd only prescribe me a week at a time. Suggested a visiting nurse to do meds weekly so I don't have access all at once. Managed to get out of that, but I can confirm it's not just one provider trying to scare me out of overdosing. It's not just the concern about its potential lethality, but everything before that. It's painful, really hard on the body, and nowhere near guaranteed. My outpatient provider I meet with monthly has told me many times that it's a nasty overdose.
less specifically, medications like that are more likely to screw up your organs. there's a decent chance you survive, and now your liver could be shot. not sure how important it is to you, but if you survive with messed up organs, then you might not be able to take some psych meds at all. not sure if things would be even worse for you without them.
I rambled a little, but I've been warned a lot about Lithium and toxicity. And none of it includes going to bed and never waking up. I strongly discourage you from using this method with all of these different meds. You'll probably just end up in the hospital, and physically damaged or worse off than before.
