Power analyses should not be based on the effect you expect but on the smallest effect size of interest. You commonly hear people say power analysis is not possible because you don't know the effect size. But this is a (common) misunderstanding of what you are suposed to do in a power analysis. You plan for the effect you do not want to miss - not for a guess of what it might be. See https://online.ucpress.edu/collabra/article/8/1/33267/120491/Sample-Size-Justification