They're all going to receive a blanket pardon.
Well, we've already crossed into "the law is what I say it is" territory thanks to the republicans, so the next admin just needs to leverage that. The GOP thinks that pardons signed by autopen are invalid [0] so I don't see what would stop the democrats from apply the same logic to ICE agents and administration, except perhaps cowardice.
[0] https://thehill.com/homenews/house/5575379-house-gop-comer-d...
To the extent that their actions are unlawful, they are often crimes under state law in the states they occur, as well as federal law. The President of the United States has no power to pardon state law offenses (and while there may be political considerations that discourage pursuing charges while it might provoke conflict with the Trump Administration, but in many cases the statutes of limitations for violent crimes under state law are not short.