This sounds like typical social media clickbait! There is simply no such thing as a universal PIN code trick that allows you to open a standard house or apartment door in an emergency.

Standard house doors operate using mechanical lock cylinders. Keypads or digital PIN codes do not exist on ordinary locks—consequently, there is no code to enter.

The background behind such online videos and tips:

Electronic locks & safes: Some inexpensive electronic locks, trash bin locks, or cheap furniture safes come with simple factory-set PINs (such as 0000, 1234, or master codes found in the manual) that many users never change. However, this is not a “trick,” but rather a security vulnerability caused by negligence.

Smart locks: Smart door locks can be opened via a keypad. While they do offer emergency features (such as one-time PINs generated remotely via an app), these must be set up by the owner beforehand. There is no secret universal code for strangers.
Dangerous myth: Videos promising that a mechanical lock can be magically unlocked using key combinations, paperclips, or lemon juice exist solely to generate clicks.
What actually helps in a real emergency:

Leave a spare key: The safest “trick” is to leave a spare key with a trusted neighbor or friend.
Locksmith service: If the door has merely latched shut (without being locked), professionals use plastic cards or specialized door-opening cards to push back the latch bolt.

Use reputable emergency services: When calling a locksmith in an emergency, look for fixed prices to avoid price gouging. Are you actually locked out right now and need help figuring out the best course of action?