So doing more looking into this it appears that what I want to do is called Morph Targets. This requires modelling a start and end point for my shape (the animated line) those two models will then be blended together to create the animation.
This requires the use of another piece of software like Blender or Maya to create the models and blend, then importing the FBX files into Unreal - I do have access to Blender, it just seems like a lot of work right now for what I’m doing, it may be something to come back to once I’m a bit more advanced.
So what I thought of instead would be an animation using the motion of multiple objects along the splines looped, creating something that looks like a ‘flow’ in the direction.
Upon clicking the box/menu these splines will appear with the animated object moving along them on a loop.
Given what I’ve looked into so far I think this will be good option that while maybe more challenging than the simplest option, also gives a better visualisation of what I’m hoping to ultimately achieve
Edit:
I’ve found this post which at first glance looks to go through what I’m now looking for
https://forums.unrealengine.com/t/animate-multiple-objects-along-spline-conveyor-belt/617024
Found it at end of day though, so I’ll have a look at it properly tomorrow.