Tolkien himself said 'I wisely started with a map, and made the story fit'. However, the geography itself isn't realistic. This is discussed in [0], with the tagline 'Middle-earth’s got 99 problems, and mountains are basically 98 of them.' In summary, the mountains are essentially linear features that create barriers useful from a plot point of view. The Misty Mountains run north-south, and form a right angle with the Ered Nimrais, which run E-W and separate Gondor from everything else. The Ered Nimrais themselves have a right-angle with the Ephel Duath, which are the western side of the three-sided square of mountains (!) that form the border of Mordor.
The main river of Middle Earth - the Anduin - runs parallel with the Misty Mountains - and itself appears to emerge at 90 degrees from the Ered Mithrin, the mountains that run E-W along the top of the Middle Earth map.
Real geographic features tend not to form right angles.
[0] https://www.tor.com/2017/08/01/tolkiens-map-and-the-messed-u...