Cost of a reno depends on a lot of things. Your best bet is to put together a detailed list of what must be done and what would be nice to have done. Then get some estimates.

My experience of bathroom renos was nowhere near $20k. One was built new in my basement and required plumbing to be run. It cost around $30k 6 years ago. The size of the bathroom was modest and fixtures, though decent quality were not "high end". The other, was a total gut of my main bathroom. The plumbing didn't move but all my materials were high end. It cost around $60k 2 years ago.

Ten years ago I paid that amount just for my shower fixtures and tiling. It it is likely only possible if you use cheaper fixtures and DIY the entire projects. Just a well made large vanity would eat a large chunk of your budget.