No items with 32x32 textures?

First of all there is not any reason to create 2 same topics within so short time. 
Next , there are two different things - the texture and the mesh (the model). In case that you do not use a custom model , the game generates one from the texture , however this generic model has some specific default size. If you change size of the texture , it just changes the resolution of the texture on the mesh . not size of the mesh. For 1.8+ it is easy to chaneg the mesh size inside its .json file.
For older versions you need create a class that extends IItemRenderer and register it using MinecraftForgeClient.registerItemRenderer(YOUR_ITEM, INSTANCE_OF_YOUR_CLASS);
So for example: using MinecraftForgeClient.registerItemRenderer(mcreator_crossbow.block, CrossbowRenderer);

In the render function of the renderer just use GL11.glScalef(scale,scale,scale) for changing the scale , for example something like this:

public class CrossbowRenderer implements IItemRenderer {
    
@Override
public boolean handleRenderType(ItemStack item, ItemRenderType type) {
return type == ItemRenderType.EQUIPPED || type == ItemRenderType.EQUIPPED_FIRST_PERSON;
}

@Override
public void renderItem(ItemRenderType type, ItemStack item, Object... data) {
switch (type) {
case EQUIPPED_FIRST_PERSON:
     renderEquippedItem(item, (EntityLivingBase) data[1], true,type);
     break;
case EQUIPPED:
     renderEquippedItem(item, (EntityLivingBase) data[1], false,type);
     break;
default:
}
}

private void renderEquippedItem(ItemStack stack, EntityLivingBase entity, boolean firstPerson) {
GL11.glPushMatrix();
GL11.glScalef(2f,2f,2f);
RenderManager.instance.itemRenderer.renderItem(entity,stack,0,type);
GL11.glPopMatrix();
}

}

I don't know if you know this, but you put your email address as your username.