Printing a web page has nothing to do with Ask Ubuntu but with your choice of browser. E.G. I'm currently using FireFox and that has an "Enter Reader View" mode in the address bar like this:

[![Screenshot of OP question][1]][1]

(The little page icon just before the <sup>**...**</sup> at the rightmost of the address bar itself)

Pressing that first and then printing prints perfectly at 150 on my printer.

So basically your question is off-topic on Ask Ubuntu itself and on Ask Ubuntu Meta, so I've also voted to close your question after posting this.
  [1]: https://i.sstatic.net/WXdNl.png