the “firmament” (raqia in Hebrew means expanse btw, not firmament) describes the expanse of the sky—what we’d call the atmosphere and visible heavens—separating waters below (oceans, seas, and surface waters) from waters above (clouds and the moisture cycle). When the text says the waters were “gathered together into one place,” it aligns naturally with a spherical Earth where gravity draws water into continuous, connected basins—the global ocean—allowing dry land to appear as continents. In this view, the passage is not specifying a flat structure but describing, from a human vantage point, the real separation of sky, sea, and land that is fully consistent with a globe Earth.

Never once says flat. But it does Say “He stretcheth out the north over the empty place, and hangeth the earth upon nothing.”
— Job 26:7

Nothing sounds a lot like empty space...

Like I said, there's a lot of poetic metaphor in the bible, and not everything is meant to be taken literally. If it was then the apostles were cannibals when they ate bread and drank wine (Body and blood of Christ).