This Stellaris mod fixes a couple of problems with the default visuals, including:
Fleets are too tightly packed and ships often clip through each other. Once you have a big and especially if you have allies, you can't even tell one ship from another. Not to mention the far bigger mess that two large fleets crashing into each other creates. Downscaling every ship type fixes this.;
You don't get a proper sense of capital ships and escort ships because the scale between ship classes increases more or less linearly and corvettes for example are just too big compared to battleships. This mod creates a clear distinction in scale between corvettes/destroyers and cruisers/battleships.;
Turrets are scaled down relative to ship sizes to make ships feel bigger.;
Engine exhaust trails and some weapon effects are scaled down as well.;
Also rescaled: starbases, habitats, stations, defense platforms and various creatures and objects around the galaxy.
Credits: Chondrite