Infinicrafts includes one custom item, so it has one texture.
The texture file is located at (assuming you extracted the .zip into a folder called Infiniresources):
You can create your own custom resourcepacks this way. Make sure to change the "parent" component based on your item, for example, "item/netherite_sword" for a sword, or "item/generic" if you're unsure.
Infiniextras (Deprecated)
Infiniextras is now deprecated. It is no longer supported and is removed from the latest versions of Infiniresources. It is however still present in version 1.0.
Infiniextras includes three custom items and a custom block, so it has four textures. The texture files are located at (assuming you extracted the .zip into a folder called Infiniresources):