Almost every tutorial you'll find is bad and/or outdated.
I recommend tossing the whole thing out and following Cadiboo's tutorials: https://cadiboo.github.io/tutorials/
You're modding a game. Seeing the game's code so you can figure out how the game works and how you can modify it seems like a bit of a necessity to me.
protected void preRenderCallback(EntityJungleSpider nttLizSt, float par2)
{
GL11.glScalef(0.2F, 0.2F, 0.2F);
}
I think this is what you're looking for: it goes in the render class. Obviously just change it to your entity and Whatever scale you want.
Oh, this is still working 1.13. I have no 1.14 version.