Scenario: A group is in a room and the Druid amongst them casts the spell “Pass Without Trace” on the whole group, boosting their Dex (stealth) checks by 10. There is nothing in the room to hide behind. Moments later the door is kicked in and a gang of hobgoblins is looking right at the group. Can they be seen? Can they hide?
Now correct me if I’m wrong, but my interpretation of this spell is a boost to stealth, and not much more (it also grants the ability to not be tracked except for by magic, but that’s irrelevant here). So if the group rolls a stealth check and the goblins roll a perception check, the goblins have the chance to see the group. I’m pretty sure of this. Where I’m less sure is if the group even has a chance of hiding with no boxes or beds or anything to hide behind. Even if they roll a natural 20 on their stealth check (boosted to 30 with the spell), do the goblins have to roll perception, or can they naturally see a hulking druid and 3 dwarven fighter allies who are just standing in the room?
No, you can’t hide in plain sight just by saying so, even with a really high Stealth buffed by magic. Rule One of hiding in 5e:
If someone can see you, you can’t attempt to hide from them.
You have find some where or some way of hiding before you can make the check to see if your hiding works. Hide first, roll the check second, always. For example (from the same link), you could all get down on the ground under your cloaks, and pretend to be lumps of rags. The goblins would see the rags, but they’d have to beat at least one of your party’s stealth checks in order to notice that they don’t belong there (and note that your DM might give the goblins Advantage if they’re intimately familiar with this room and would usually notice something out of place).
So step one, find a hiding place. Do this like it makes sense in real life, using camo, breaking your outline, staying motionless deep in confusing shadows, getting up above the normal height people think to look at, etc. Make at least some minimal attempt to leverage that enhanced bonus. Then, and only then, can you roll your Stealth to see if you execute the method you thought up.
Now, the spell itself gives you some ideas for free, but you have to use them. Work those shadows, don’t just stand around. Say how you’re hiding, then find out if it worked.
No method, no Stealth check to see if the non-existent method works!