The Current President's Term Must End
No matter what else happens, Article II, Section I of the Constitution sets the President and Vice President's terms at 4 years. Whether there is a new election or not, they must vacate their offices January 20.
Congress sets the date of the election
The same article gives Congress the ability to set the specific date of the election. They have met this obligation through a law (US Code Title 3, Chapter 1, Section 1) which says:
The electors of President and Vice President shall be appointed, in each State, on the Tuesday next after the first Monday in November, in every fourth year succeeding every election of a President and Vice President.
Would it be reasonable to pass a new law?
The election is currently scheduled to take place in 9 days. Should Congress pass a law unusually quickly, the President would need to sign it before it had any legitimacy (or the President would have to veto it and Congress would need to override that veto). Unless the President and Congress are both completely on board, this is highly unlikely to happen.
For discussion, let's suppose they passed this act and it became effective on Monday, October 31st. At this point, states and parties have already heavily advertised the date of the election, election sites have been chosen and election workers hired (or recruited) for those dates. Changing the date of the election would require a massive amount of coordination and likely be perceived as unreasonable by the states and parties.
Many states also have laws which set the election date. For example, Kansas has KSA 25-101(a), which requires an election every-other year on the same date as the federal election.
State legislatures may not be in session, which means it would be impractical for them to change their laws this quickly. We can only speculate what would happen, but it would likely mean a sleepless night for Attorney Generals across the nation. It could mean that state elections happen on the required date, but federal elections happen on a new day.
Why would they?
Accusation of having committed a crime does not prevent someone from running for the presidency or being elected. Nothing in someone's criminal history prevents them from being president. There would be no (legal) reason to change the election date.
If voters decide this issue is important, they can choose not to vote or vote for someone else.