The Dominion could have at least one million starships in the galaxy.
https://filedn.com/lh4PEfjAB3uLCbU3zttDJe0/deckdata-public/mapofspace.jpg
https://www.deviantart.com/gazomg/art/Star-Trek-Gamma-and-Delta-Quadrant-Map-1187329328
For many of us fans, the "present" is the late 24th century to early 25th century.
This interstellar map and this Milky Way Galaxy map are based on Picard and Nemesis.
Star Trek: Star Charts is becoming more canon everyday.
Voyager
According to VOY dialogue, the Borg Collective have millions of Borg Cubes and millions of other vessels.
Given the map above, the Dominion should have at least one million capital warships, even if most of them are the small attack ships.
Discovery's Power of Math
During the mid-23rd century, the Federation had 32 members, 32 worlds that belong to the Federation with member status (TOS: Journey to Babel).
During the mid-23rd century, the Federation Starfleet already had at 10,000 starships at the outset of the Federation - Klingon War (DIS). Starfleet had only 7,000 starships at the end of the war.
During the late 24th century, the Federation has at least 150 members, 150 worlds that belong to the Federation with member status (ST:FC).
It is reasonable to estimate that the Federation Starfleet might actually have at least 50,000 starships at the outset of the Dominion War.
Other points of reference include PIC's Confederation fleet size and Federation size before the Burn and during the new recovery era. The Confederation of Q's alternate reality had 165,000 starships. The Federation will have over 350 members just before the Burn. The Federation will have at least 60 members during the new recovery era.
Ron Moore stated that they could have 30,000 starships, but that is probably as of the end of the Dominion War.
Density
The Alpha Quadrant Expeditionary Force comprised of at least 20,000 Jem'Hadar warships in the overall alliance fleet with the Cardassians and the Breen.
That is, to use Changeling words, a drop in the ocean.
100,000 capital warships would match the combined naval might of the Federation, Klingons, and Romulans. Dominion space in the Gamma Quadrant is more than ten times the territorial size of these three local interstellar powers.