In a comment you say you are interested in internal reliability. Maybe the most common measure of that is Cronbach's alpha, although some people question whether it is the best.

For this (and other measures of reliability) you don't have a hypothesis test and some aspects of power analysis aren't useful. But, as N increases, the accuracy of alpha will increase.

Googling was less productive than I thought it would be, but I did find an online calculator for this. (If there is link rot, then this citation may help" APA: Arifin, W. N. (2023). Sample size calculator (web). Retrieved from http://wnarifin.github.io)

That calculator is based on Bonnet (2002). Sample Size Requirements for Testing and Estimating Cronbach's Alpha. J. Educational and Behavioral Statistics. 27(4) 335-340.

Note that, above I said hypothesis testing wasn't the issue here. It's not that you can't do hypothesis testing on alpha, it just doesn't seem apropos here.