In short, not at all.
The last MacBook Pro Model that was customizable in terms of RAM & Storage was from the Mid 2012 ( A1286 & A1278 ) Unibody Model.
SSD Storage on other hand was customizable on all newer MacBook models ( Late 2012 to Mid 2015 ( A1398 Family )) and you could of upgrade the storage aka the “SSD”
Unless you’re a very experienced logic board technician with a high level of repair knowledge that can perform micro soldering, beginning Mid 2016 the SSD is no longer interchangeable on any and/or all Apple laptop models.
So, if you’re planing to buy a new MacBook laptop going forward, make sure that you consider that and buy it with the amount of RAM and storage(SSD) that you think you could possibly need later. It isn’t easy to replace the embedded drive yourself.
It is not something that you can upgrade in any way after the fact.