Either ChatGPT o4 or one of the newer Google models should handle that, since it's a pretty common task. Actually there have been online curve fitters for several years that work pretty well without AI, such as https://curve.fit/ and https://www.standardsapplied.com/nonlinear-curve-fitting-cal... .

I'd probably try those first, since otherwise you're depending on the language model to do the right thing automagically.