Its not just ICE, its clear Trump intent for law enforcement (and not just federal) from even very early on in his first term, where a highlighted priority was terminating then-active federal enforcement actions against state law enforcement agencies for violations of civil rights. Lawless “law enforcement” has been one of the most consistent overt priorities Trump has had.
Yes, but ICE has been fast and loose with the law for a long time so they’re starting without something like the military’s culture about lawful orders, appropriate use of force, etc. As in so many areas, past presidents ignoring the problem left it ready for scaled up abuse.
ICE leadership below the top level is currently being purged, and apparently replaced with officials transferred from Border Patrol, because ICE’s approach and culture is more targeted and criminality based, and many of the biggest abuses so far in the immigration crackdown blamed on “ICE” have actually been carried out by Border Patrol (its not a coincidence that much of the current controversy in Chicago centers around thhe regional Border Patrol commander.)
While ICE is being massively scaled up with the intent that you describe, its not unique in kind or even the worst by degree of the agencies involved in terms of either historic or current lawlessness. It's just the one with the public mission most in line with the propaganda cover chosen for Trump's totalitarian efforts.
I think ICE's expansion + their massive legal discretion that goes beyond typical law enforcement is just he perfect place to put thugs. ICE by design is just the spot to have those folks, sadly.