Speaking about resistance as mentioned earlier, I would like to take a moment to discuss damage resistance (DR) in PF 2e for those that might not be familiar with how it differs from D&D 5e…and the difference is pretty significant.
In D&D 5e DR just halves the damage taken from a source that the target is resistance to. In PRF 2e, DR is much more valuable to a PC and also much worse for the PC’s if enemies have damage resistance. Damage resistance in PF 2e is more like a resistance wall one has to get over; the damage resistance is a threshold that a PC has to do more damage than the threshold to do any damage at all. So if an enemy has a DR of 5, a PC will have to do more than 5 damage to do any damage at all.
I bring this up because I have noticed some battles where folks are scoring lots of hits on the enemy and happy about that, but then end up being disappointed when every attack does no damage. I’m not trying to call anyone out or criticize anyone’s play style, I just want to bring up some points that may help folks deal with DR or recognize it in a battle and adjust accordingly to get the most out of your character in a fight.
Watch your damage rolls in the chat in fights to see if a enemy has damage resistance and also watch others’ damage in the chat in fights, this way you will get an idea of what the DR threshold might be, or at least close enough to gauge whether your attacks are going to do any damage. Watching the damage chat of others’ attacks can also clue you in on what type(s) of damage the enemy is not resistant to or is vulnerable to in case you find your attacks are not being effective damage wies.
Alright it’s story problem math and formula time! Let’s take the rat and rat swarm fight that we are currently in; the rat swarms are consistent with D&D 5e in that they have DR, I think most if not all swarms in 5e and probably in PF 2e have DR. I was watching the combat chat closely once I finally got in the game and I’m guessing the DR is 5…ish. Once you think you have determined (or closely approximated ) the DR threshold look at the max damage you can do for the attack you want to use and decide how you want to gamble on doing damage or not. Say you are using a dagger and your damage bonus from stat is +2, your MAX damage is going to be 6 which would do 1 damage past the DR of the rat swarm if the DR is 5. Now look at in terms of percentages., to do 1 damage you are going to have to do 100% damage; anything less does nothing. Now say you are using a longsword and your damage bonus from stat is +1, your MAX damage is 10 so you need to do at least 60% damage to do 1 damage past the DR. In the case of the dagger wielder, it might be best to focus on targets without the DR and best for the longsword wielder to go after the targets with the DR. Of course you also factor in various class/ability/race/whatever variables that affect damage output for individual attacks to decide your odds on being able to damage an enemy with DR. And keep in mind that doing multiple attacks is not going to stack damage against the DR, the DR is figured for damage from each individual attack damage.
In my case I did not play smart as per the info above, I attacked the debuffed, stunned, blinded (which doesn’t mean shit) paralyzed etc rats and should have left those to others while I went to work on the rat swarms as I am a longsword melee attacker with spell damage I can thrown in there for an extra chance to do damage. My physical longsword attack is more likely to get around the rat swarm DR than any cantrip I can load into my weapon with Spellstrike. If I had any lvl 1 spells available to use with Spellstrike I could have a chance to do even more damage, but I uysed up all my slots and we haven’t had a sleep yet. But I was tired and irritated and not thinking all that straight and just wanted to kill rats I guess 
OK that all sounded shorter in my head. Have fun reading it, not reading it, skimming it whatever. I hope maybe it did some good for somebody maybe. Oh and Dr in Pathfinder is total cheese, it’s more like a quasi-pseudo mini-damage immunity wall especially against low lvl PC’s.