Since I'm seeing people claiming that he'd plead 5A when questioned -

A defendant that chooses to testify in court has waived their 5A rights. A prosecutor can not compel a defendant to testify--that's where 5A comes in--but if a defendant chooses to testify, then they may not refuse to answer relevant questions. Answering questions untruthfully if you've chosen to testify is, by itself, a crime. If a defendant lies, which Trump is almost certain to do, then the prosecutor can call rebuttal witnesses to prove that the defendant was lying under oath.

Witnesses--people not on trial--can plead 5A and refuse to answer questions. Prosecutors will sometimes give witnesses immunity from prosecution for truthful testimony; that negates the 5A interest.