The Nether is where fog hurts the most: the thick red haze normally hides terrain, mobs, and lava from more than a few blocks away. With No Fog Mod installed, that haze is gone, but you still need to set yourself up to actually use the extra range.

Confirm the fog is actually gone

Load into the Nether and look toward the horizon. If you still see the reddish distance fade, check that the mod is loaded for the correct mod loader profile and that no other visual mod is re-adding fog. Once it is working, distant netherrack, basalt, and soul sand valleys should read clearly instead of dissolving into red.

Make the extra range useful

Raise your render distance in video settings so the game actually draws the chunks you can now see. No Fog Mod removes the fog layer, but it does not force distant chunks to load.
Bring torches or another light source. Without fog, dark caves and fortresses are visible but still unlit, so lighting the path keeps you from walking into lava.
Use the clear sightlines to spot ghasts, blazes, and piglin structures before they spot you.
When bridging over lava lakes, look down periodically. Fog used to hide the drop; now you can judge distance and plan safe crossings.

Combined with a higher render distance, the mod turns the Nether from a claustrophobic maze into readable terrain.