How does the presidential pardon work for unknown crimes?

I always thought the presidential pardon was for people wh have been convicted of a crime. But if Trump wants a pardon for himself and has not been convicted, can that still work?

Can a president pardon someone for a crime for which he/she has not been convicted?

Can a president give a blanket pardon possible crimes? (Ie: to say ’ he is pardoned for any crimes relating to X ').

Can a president give a pardon for a future crime?

Wasn’t Ford’s pardon of Nixon a blanket pardon for all federal crimes Nixon may or may not have committed while in office?

I think it’s roughly equivalent to sincerely apologizing to your spouse when you have absolutely no idea what you did wrong.

FactCheck supports this position:

Here’s the relevant text:

A couple of howevers.

Presidential pardons apply only to federal crimes, not to state crimes.

They apply only to actions in the past; they cannot pardon future crimes.

Someone who has accepted a pardon no longer has a fifth amendment right against self-incrimination for that offense and can be compelled to testify/

A pardon, therefore, is not a magic spell. It has real-world limitations.

Ok, but isn’t the self-pardon some sort of admission to culpability? That would be a big step for our baby president.

Yes, but when or if someone is facing real jeopardy with real consequences, they can swallow their pride reeeaaal quick. In theory.

Ford wanted Nixon to express contrition before the pardon, but Nixon refused, believing he had committed no crimes. Ford issued the pardon anyway. Afterward Nixon expressed regret for not handling Watergate “decisively or forthrightly,” and said he made mistakes, but never admitted to a crime.

Not necessarily. If a President thought he was innocent but was being unfairly hounded, he might pardon himself just to stop what he believes is a witch hunt.

But I don’t expect Trump to pardon himself, nor do I expect him to be charged with any federal crimes for his time in office.