No player sold for £100m or over has actually been worth the money, so no, I don't think Sancho is worth that amount. Not even Mbappe or Ronaldo have been worth the money their clubs have spent.
What has PSG won with Mbappe that they wouldn't have won without him? Nothing.
What has Juventus won with Ronaldo that they wouldn't have won without him? Nothing.
Both clubs would have won the same things without them, so the investment has not had a tangible impact which you expect from a player of that amount.
I hope clubs are wising up to the fact that spending £100m on a single player is a bad idea. For some reason, clubs have got the idea that the next Messi/Ronaldo will be found so soon. Players of that standard come around rarely, so it is stupid to throw around ridiculous amounts of cash just for the very small chance of unearthing the 'next greatest player ever'. So, Sancho is not worth it.
Dortmund probably don't think he is worth that much either, but buying clubs have been so stupid recently that I am not surprised they asked for so much. Especially when they didn't even want to sell him.