I need to create expressions to a shape layer's size and postion however I'm unable to because menu options are missing from the tab within the shape settings
Imported a custom AI file into After Effects and selected the Create Shapesfrom Vector layer option.
Once converted the AI file updates to a Bezier shape rather than Parametric. I'm needing the size option to appare in the drop down menu under the path menu however the size option is missing and the only option is path.
The only time a shape layer seems to convert to Parametric is when you select the shape tool and manually draw out your shapes. However I'm needed custom shape styles that were easier to create in illustrator so thats why its brought in rather than redrawn in After Effects.'
No such thing and even if there were, the mere use of specific layer styles might still cause data to be converted, in a worst case even to flattened pixel data. You are operating under wrong assumptions. AE's shape layers are not a complete re-creation of AI with motion, they only support a limited set of AI features at all.
More than 90% of the users that convert vector paths to shape layers are wasting time and energy and removing a lot of functionality. Unless you are going to animate a vector path or use a shape layer animator like Trim Paths, or you are going to use the C4D rendering engine and extrude a shape layer, there is absolutely no reason to convert a vector layer to a shape layer.
If you need access to the size property of a parametric shape you need to create that shape in After Effects.