Bleu_2ay's Spider Model
This resource pack completely transforms the appearance of Spiders and Cave Spiders in Minecraft, giving them a modern and realistic design.
The main changes include separate modeling of the cephalothorax and abdomen, addition of pedipalps and chelicerae, as well as thin elongated legs, making the spiders significantly more anatomically accurate. Cave Spiders received a separate model with their own unique features, including a different eye color.

The resource pack requires Entity Model Features mod to work and is also potentially compatible with Optifine.