You can get the STL for any model on MakerWorld. Just hit the down arrow to the right of the green "Open in Bambu Studio" button and select "Download STL/CAD files". If that is ever not an available option (though I believe they are now automatically generated by Bambu Lab now even if the maker doesn't upload them), just open in Bambu Studio, right click on the model, and select, "Export as one STL".