Keep in mind if you are untrained you do not add your level to your check, it is just the raw Ability modifier. So as you level up, there is a much larger gap between someone who put no investment in an skill (untrained) vs someone that has put even a moderate level of investment (trained or expert). Also keep in mind there are two types of DCs in PF2e--simple and level-based. Level-based DCs are for things that are there to challenge a party of that level, and thus may appear at various levels of difficulty (things like you want to persuade a level 6 NPC, identifying a 5th level spell or running across a quicksand hazard that is meant for a level 9 party etc). Simple DCs are for things that should be the same difficulty no matter the level of the character interacting with them; they just exist in the world (stuff like climbing a tree, breaking down a door, or balancing on a tightrope). This may be closer to what a 5e player is used to since you can set their DC based on what a Trained person should be able to easily do or what an Expert could easily do etc. There are examples of these for each of the Skill actions (it may only be a DC 15 Athletics to break through a glass window, but a DC 30 to break down a heavy wooden door). An 8th level character untrained in Athletics with a +4 Strength only has that +4 to do either (so can only succeed, but not crit succeed at the door on a natural 20), but a character with +4 Strength that's an Expert in Athletics has +16 so can only fail (but not critically fail, at breaking the glass even with a natural 1).
Keep in mind if you are untrained you do not add your level to your check, it is just the raw Ability modifier. So as you level up, there is a much larger gap between someone who put no investment in an skill (untrained) vs someone that has put even a moderate level of investment (trained or expert). Also keep in mind there are two types of DCs in PF2e--simple and level-based. Level-based DCs are for things that are there to challenge a party of that level, and thus may appear at various levels of difficulty (things like you want to persuade a level 6 NPC, identifying a 5th level spell or running across a quicksand hazard that is meant for a level 9 party etc). Simple DCs are for things that should be the same difficulty no matter the level of the character interacting with them; they just exist in the world (stuff like climbing a tree, breaking down a door, or balancing on a tightrope). This may be closer to what a 5e player is used to since you can set their DC based on what a Trained person should be able to easily do or what an Expert could easily do etc. There are examples of these for each of the Skill actions (it may only be a DC 15 Athletics to break through a glass window, but a DC 30 to break down a heavy wooden door). An 8th level character untrained in Athletics with a +4 Strength only has that +4 to do either (so can only succeed, but not crit succeed at the door on a natural 20), but a character with +4 Strength that's an Expert in Athletics has +16 so can only fail (but not critically fail, at breaking the glass even with a natural 1).
You are the moistcritical of DND!