In 6 months, they greatly expanded ICE, contracted with a right wing foreign government to build special "prisons", used "probably military" planes to fill with people given no due process before being sent to countries in Africa themselves in crisis.
ICE now has a huge budget, but even that budget likely does not show how the assets they have as they use money and resources approved for other things.
In addition, they are working to make all police forces work for their goals. This will make the police less successful at their police work as some people can't come to them when they know of problems. Not to mention, some of their time will have been diverted.
On a separate path, they are working to eliminate birthright citizenship. Reading between the lines, I think this is because of their belief in the concept of "anchor babies". If they are successful, there will be no future anchor babies. Next step may be something they cynically might call keeping families together where children born before this change but under 18 (or 21), even though American citizens, will be deported with their parents.
It was already said that you can't just get numbers like 12 million people out of the country. In reality, we are seeing things most of us never would have believed could happen especially as they obviously planned starting blue states.
I suspect Steven Miller and others spent a lot of time planning what they would do and as soon as Trump was sworn in started acting on it so quickly it has been hard for us to even take in all of what they are doing.