Intel HD 620 is really far below the minimum system requirements listed for Stormblood. The best integrated graphics you can find is below the minimum system requirements. A GTX 750/R7 260X or higher is listed as the minimum at a resolution of 1280x720, so it's honestly impressive that you're even pulling 15fps on the standard laptop preset. If you can get it up to 30 on the lowest settings and lowering your resolution, you will probably be okay questing and running dungeons and such. The Lenovo T470 is considered a business laptop and was not intended for heavy gaming.

You could pick up an external GPU enclosure since that laptop has a thunderbolt3 port, but you're looking at hundreds of dollars for the enclosure and another $150+ for a GPU (and then you might still run into problems with that processor--I'm not sure how well those U series cpus will handle an MMORPG with lots of players around). You'd probably be better off just returning it and buying a gaming laptop or a PS4 at that price point.