How can one determine if a sample size is representative in scRNA-seq analysis?

Question

[fifty_fifty]

Potential findings from scRNA sequencing and downstream analyses can include novel cell types and ligand-receptor interactions between some cell populations. Those downstream computational analysis methods include statistical testing such as Wilcoxon test for finding differentially expressed genes to annotate cell clusters. But what about sample sizes and cell numbers in each sample? In other words, how do I know if the number of samples and sequenced cells in them are enough?

There are tools like scPower and POWSC to find an optimal number of samples, cells per sample, and sequencing depth BEFORE sequencing. But how do I find if the second-hand scRNA-seq data I am using is sufficient?