I think the misconception is to think that POTUS have all the powers and is omnipotent. A lot of forces are at play. It would be interesting to ask the C's the percent of real power Trump have.
Recall that presidents receive orders, not the opposite. Trump is on a thin line.
That's a very important point to remember. Having said that, a POTUS that is trying to not just go blindly along with any agenda handed to him can still have much more power by simply saying "no" to things than a POTUS who has no backbone and will just do everything that the deep state hands to him.
Trump is a good example of a POTUS of the first category IMO. While such a POTUS has still not all that much ability to effectively do anything (especially in the long run), he does have the power to say "no" on major issues such as war, even if that then just turns out to be symbolically at the end, because the real movers and shakers just do it anyway. By this ability to say "no" he can for example delay stuff until another more fitting President comes in who just goes along. We have seen Trump say "no" on many war fronts (remember how they pushed him into war with Iran, North Korea, Syria, Venezuela, Ukraine, Russia, China etc?) and other important issues. Much more so and much more openly IMO than any other POTUS in that first category before.
I also think that this legal and philosophical ability of the POTUS to say "no" is what irks those Psychos the most. They can't accept anyone on that position who dares to say "no" on major issues handed to him. Which suggest to me that there are still legal and philosophical grounds in which the POTUS has a lot of power by saying "no" and the Psycho-creatures can't do much about it.
This ability and power that the POTUS possesses to say "no" also creates great conflicts in the ranks below, since there are those many people, (generals, officials, soldiers and ordinary people for example) who do still adhere to and believe in the idea of the POTUS being the "Commander in Chief".
For example; when POTUS decides to pull US-Troops out of Germany, Syria, Afghanistan (as Trump has tried repeatedly) something like the following happens:
1: POTUS decides to say "no" to have those troops stay there
2: The "real" movers and shakers above and below Trump (many psychopathic types, I would assume) say "no" to that "no" of the POTUS, despite him being the "commander in chief"
3: Other types of movers and shakers (generals, officials, soldiers and ordinary people) that rank below the "commander in chief" believe and adhere to the idea of the "commander in chief" and want to oblige with POTUS "no" command, since, after all, he is the commander in chief, right?
4: Some movers and shakers start the process of getting troops home while others do the exact opposite, since they don't follow the commands of the "commander in chief".
5: A conflict arises between those people honoring the idea of "commander in chief" who is supposed to represent "the will of the people" and those who do the bidding of the deep state.
6: A lot of back and forth happens and the deep staters win because they have the right people on the ground in Germany, Syria, etc. who don't follow what POTUS says.
7: Since a general or soldier usually has to just follow what the officer in the rank directly above him says, many soldiers don't question that decision from that immediate superior, even though the POTUS commanded something different. Just someone in the chain of command is needed who does not oblige with POTUS (or his superiors) decision and those below him will follow, mostly without question, in the assumption that the superior also just followed orders that were in the end ultimately really coming from POTUS.
8: Troops stay there
So a lot of what the POTUS does and has power over depends on the character and integrity of POTUS himself. If he is a psychopathic type for example, something reversely might happen in the ranks below; If Psycho POTUS says "we start war" many of those ordinary followers below his rank will believe in the idea of "commander in chief" and do what he says without questioning as well, while the real movers and shakers below and above the president are happy about it and of course also follow along. If a more or less normal human being is at that position, things can be quite different. In that case the phrase "the fish stinks from the head" has a lot of bearing.
On the question of war, a similar scenario happens while the POTUS might have even more support from the ordinary folk who believe in the idea of "commander in Chief" even if it doesn't exist in reality. If POTUS says "no" to war, there seems to be quite a bit more difficulties for the psychos to just do it anyway, compared to the pulling troops out scenario above.