In 5th edition you are not supposed to know; this is what the Passive Perception score is for. If you're not specifically looking for anything, the DM is supposed to use your Passive Perception instead of rolling a check that would alert you to the existence of something hidden; if you are specifically looking, you roll Perception whether or not there is anything to find.

For a PC game, it makes sense, too, for replay value

they could add a cheat mode called "seer" or something, for people who want to do that and they could set their own perception boost.
iddt

There is a mod on Nexusmods to hide failed perception checks, but it's still beta and doesn't seem to work properly yet. Might be worth tracking.