So I've been looking everywhere for a way to make this bottle and nozzle cap look as close to the real version as possible. I've used many different node setups I've found online to see it on my model, but I can't seem to get the same look as the real bottle. I hate to sound like I'm wanting anyone else to do the work for me, but I've never really used node for anything other than applying PBR textures. I tried changing the transmission value and adjusting the roughness, but it just seems like glass. Maybe I should remove the thickness of the bottle, so the fluid inside will look like it does in real life, but I used reference photos to make the model as accurate as possible. I just assume transparent plastic is tricky.
I think for the proper plastic, you play with mixes here of translucency volume scatter and glass. for glass the ior has a huge effect on the reflections (remind plastic has higher IOR usually). But also important is to have some background for the glass to reflect something, i added one, a few more tiny tricks in it as well, adding a light with a shader to get more play in the light, its subtile
also the color of the light isnt white. and I scaled the purple part a bit.
if you like to check here are the shaders:
if you like the screw-glass part to be more white on top, add some white object above it (make a light studio environment), so then its possible to reflect that.