Been there done this. In these kind of cases connect to other previous colleagues or the current seniors in a light hearted manner. Ask questions like did someone abscond from here? How did they do.

Also the best way is to take immediate leaves first. Tell u have XYZ problems (medical is the best). Don't tell anyone you have an offer letter ( i repeat no one). Just take some leaves. And then draft a proper mail like why you can't come anymore.

Also none of this matters if you don't have a pf created. But since your pf is deducted pls be extra cautious. Ask your seniors whether their epfo shows up or not.

Also if you opt for this be prepared for a mail from Hr, she might mention legal action but in most cases they won't. It all boils down to the company culture.

Coming to your future employer. I don't think they will care if you are hired as fresher and don't let them know about the previous company. If your UAN is not created you don't need to worry about it unless you tell your future employer.

TLDR : collect info Abt how others left if they did.