Bible mentions the stationary Earth, the Firmament, the waters located above the Firmament, the Foundations of the earth, the shape as circle, the extremities and so on:
THE CIRCLE
(Proverbs 8:26-27) "He had not yet made the earth, or the fields, or the first atom of dust in the world. When He established the heavens, I was there; when He drew a circle on the surface of the deep."
(Isaiah 40:22) "It is He who sits above the circle of the earth..."
A circle is a flat surface in two dimensions where all points are equidistant from a single point called the "center."
Circles also exist on a sphere, being pretty much what you see from any angle. So, mentioning a circle in no way implies "flat". You do see that, no?
THE EXTREMITIES
(Daniel 4:10-11) "I looked, and behold, there was a tree in the midst of the earth of great height. The tree grew and became strong, its top reached to the heavens, and it was visible to the ends of all the earth."
(Job 38:13 TMN) "...to take hold of the ends of the earth, so that the wicked might be shaken out of it."
(Deuteronomy 13:7 BLS) "...from among the peoples who surround you, near or far, from one end of the earth to the other."
Not only does a spherical earth lack a center, but the verses mention extremities. It goes without saying that a spherical earth has no extremities.
Of course a sphere has a center. Did you learn nothing in school? A sphere is a circle, revolved to form a 3D representation. Since a circle has a center, a sphere must also.
I can't explain much about the Bible. But the mention of "extremities" is quite a reach to say it states the earth is flat. You are really reaching with this one.
THE WHOLE
(Matthew 4: 8 TMN) "The Devil took Him to an exceedingly high mountain, and showed Him all the kingdoms of the world and their glory."
On a globe, no matter how high one goes, one would never be able to see the entirety of the world.
Not totally true. All the earth, known at that time, is visible in one view from a great distance.
Meanwhile, there is no "firmament" or most of the things mentioned in the Bible, which no one has ever actually discovered. The Bible is a work of fiction, which many confuse with the word of God, because it is pretty old. But, it's not so old that we don't actually know anything about its origins.
So, I stand by my statement.