So, I've been running the PF2E beginner box, which is like a tutorial adventure, for a group of 5 people (we play as long as at least 3 show up). The players had the option of playing any of the pregen "iconic" characters for Pathfinder. So far, we've had a fighter, witch, monk, swashbuckler, and summoner. Of those, only the witch has any sort of healing, and the witch player couldn't make our session last night.
The players went into this room that is meant to be like an optional miniboss (but there isn't really a way for them to have known that). The miniboss is this fire elemental rat that is supposed to teach you how "persistent damage" works. It's a very tough fight, and the elemental has a lot of defensive options like a cloud of smoke around it. Eventually the rat killed two party members (the swashbuckler and the monk), and one more (the fighter) went unconscious but didn't die. The last player (summoner) got chipped down to like 3 HP but was able to drag the fighter out of the fight to safety.
I think it was a good learning opportunity for the players that you need to be tactical and work together in PF2e, since they basically just all tried to attack the rat in melee. It also shows the value of having support characters in the party.
Going forward we are going to complete the beginner box, the two players who lost their PCs are going to play new pregens (bard and investigator). I'm hoping the players don't get too disillusioned with PF2e because it is very difficult at times.
I'd love to hear other Pathfinder GMs' thoughts. I'm still new, so it's possible I was doing something wrong, but I think I ran that fight the way it's meant to be run.
I don't think you've done anything wrong.
From other professional GMs in a variety of systems:
In order for any fight to be remarkable in any way, character death does need to be on the table.
If your party is consistently winning without feeling like they were in real danger, what is even the point of combat? They might feel good about flexing their abilities and mopping the floor now and then, but if every time a roll for initiative happens doesn't feel like "we might die" then combat becomes a speedbump, and not a thrilling edge of your seat experience.
I think because a lot of GM's run a game where they don't feel comfortable killing characters, players lean in to the notion that the only way to end combat is to win the fight. So players end up putting their characters in these absolutely suicidal positions behind enemy lines for "flanking" advantage but then get surrounded themselves. They play on the assumption that Damage per round is the metric to min-max, if you can just reduce all the enemy hitpoints to 0 before yours, you're golden.
The way you described it, as the rat eventually taking people down, and chipping down the players health... It sounds like at no point did anyone consider running away when their HP was low, aside from the last guy standing dragging someone else out with them. It sounds like the players decided it was a fight to the death; so they can't be too upset if they're the ones who died.
They could have decided it was not something worth dying over, and played accordingly.
I definitely wouldn't say the players have been coasting through without feeling threatened. I think almost every fight in the beginner box has had either someone go down or a significant expenditure of resources. I'm not afraid of killing PCs, but in my previous experience in D&D 5e, it never happened. A big part of the reason for my group playing through the BB is to recalibrate everyone's expectations. 5e pulls a lot of punches compared to Pathfinder, and I want the players to understand the deadlyness of the system before we start a real campaign.
In fact, they did consider retreating from this fight. But they weren't committing to the retreat, which led one player decided to Leeroy Jenkins back into the room. I think that was the point where it went from "losing but we can escape with our lives" to "some of us are going to die here"