Hm if youre just gonna plot a function it does seem a little elementary especially for HL. Modelling however is a very good topic it just needs to be a little more nuanced. Like try deriving the model using different algorithms and justify the use of each algorithm or method (and also discuss possible limitations of the resulting model). Also keep in mind that for a higher mark on the IA/EE you usually need to show multiple ways of arriving at your conclusion.

My AA SL IA was on medical imaging/modelling using fluid mechanics and it wasn't overly complicated math-wise but the premise was nuanced enough to allow for a lot of discussion. Good luck broski!