Not every encounter has to be a fight. There's no rule that say that. Why would you assume every single creature you see must be a valid target to kill? And a level-appropriate target at that. That's a bizarre assumption to make. Yes, I'm aware it's a fairly common assumption amongst D&D players, but that doesn't make it any less bizarre. Just because you see a "monster" doesn't mean you have to fight it.
If you're standing in the starting-village square and an adult red dragon shows up in front of your 1st-level character...what you do is up to you. Do you fight? Do you talk? Do you run? If you choose to fight, that's 100% your fault. If the DM forces a fight, that's 100% their fault. The options are not "fight and win" or "give up and quit". There's a literal world of options between those two. Negotiation. Talking. Seeing if the dragon wants to offer a quest. See if it makes a demand. Have a conversation. Most DM's aren't going to throw an adult red dragon at a 1st-level party expecting a fight. They'd likely assume the players were smart enough to not charge in guns blazing. If they players are dumb enough to charge...that's 100% on them. If there's a rumor of an adult red dragon lair a few miles away and your 1st-level party decides that sounds like a smashing idea for a first adventure...sorry, that's 100% your fault.