Overview
The main idea is to subtract the Object Position from the Absolute World Position then get the z component to control the amount of the liquid inside the bottle.
Another cool trick is to distort the uvs of the bubbles texture using a Perlin Noise which gives this cool fizzy effect.
Another cool trick is to distort the uvs of the bubbles texture using a Perlin Noise which gives this cool fizzy effect.

Unreal Material Editor Graph

Shader
Textures
As for the bubbles texture, I created a simple ring shape, added a bit of blur to smooth it out and then added it to a tile sampler.

Substance Designer Graph View

Bubbles Variant 1
