so no esoteric or uber powerful being jelped out the Feds?
How big was this conflict? The one you know
OK, so, it's kinda complicated?
Was there a point of intervention by super powerful beings in the Federation's favor? Yes. However, in some respects that can be argued as those aliens balancing the scales since the only reason the war could even take place was because those same aliens had built a wormhole connecting Federation frontier space in the Alpha Quadrant to the Dominion frontier space in the Gamma Quadrant. In other words, they were both enabled the war to happen in the first place and stepped on the scale ONCE, after a lot of convincing, and while it was a critical moment, it was the only time they did so.
For the uniformed, in Star Trek the Milky Way Galaxy is divided into four quadrants. The Federation straddles the Alpha and Beta Quadrants, with Sol being the dividing point. The Klingons and Romulan Empires are both in the Beta Quadrant while the Cardassians and Bajor were in the Alpha Quadrant. The Dominion was in the Gamma Quadrant, thousands and thousands of lightyears on the opposite side of the galaxy from the Federation and the only reason either side could even begin to contact each other was due to the Bajoran Wormhole, which connected the Alpha Quadrant to the Gamma Quadrant. This wormhole was not a naturally occurring one, but rather, an artificial one constructed by the mysterious "Prophets" a-temporal energy beings who lived in the wormhole but were "Of Bajor". Thus, the only reason the Dominion and Federation came into conflict was due to the wormhole and once, after considerable cajoling by Sisko, the Wormhole Aliens disappeared a Dominion Fleet that was about to attack Deep Space Nine, though in the long run all it did was buy the Federation a little more time. The vast bulk of the war was fought conventionally without any other interventions.
As to the scale of the conflict. The Dominion War is very much Star Trek's equivalent of World War 2. Most folks talk about it as Dominion vs Federation, but that's due to those being the leading factions on either side. The actual faction breakdown was The Dominion, the Cardassian Union, the Breen Confederacy, and other smaller powers VS the United Federation of Planets, the Klingon Empire, the Romulan Star Empire, and other smaller powers.
Note: historically both the Klingon Empire and Romulan Star Empire were consider near-peer powers to the Federation. In one timeline the Klingon Empire was actually winning a war against the Federation. So these were not some small powers, the Feds, Klinks and Rommies are the Big Three powers of Star Trek prior to the Dominion showing up and pretty much dominated all politics in their regions uncontested save for each other. That those three powers were united on the same side is very much having the US, UK, and USSR on the same team... it's a LOT of heavy firepower. The Breen were a longstanding peer opponent of the Romulans who brought some very... interesting tech to the war, and the Cardassians were, effectively, the Sick Man of the Alpha Quadrant.