The German Collection of Microorganisms and Cell Cultures provides the Cell Dive Portal which allows you to access STR and RNA-seq data for most of their cell lines. There are also Whole Exome Sequencing panels for many cell lines available, but afaik not easily accessible - e.g. here for 100 blood cancer cell lines.

I suppose other Biobanks have also sequenced their collections in the meantime. But the maximum you can find for cell lines are likely panels in the hundreds. For larger scales, I presume you would need to use primary tumor material?