can I upgrade my MBP 2017 13 ssd?

Check everymac.com web site for your model specifications including upgrade options. I'm afraid yours is likely to be one of those with no options. Most Macs made in the last 4 years or so can't be upgraded after purchase (which IMHO means many are going to lose a lot of resale value to people like me who are prepared to buy an older computer but not one locked into a 5 year old configuration).

For all the 2016 and 2017 (and likely 2018) TouchBar models: The components representing the SSD "drive" are soldered to the board.

For the non-Touchbar models, everymac.com has this information it its "related articles":

However, in an unexpected surprise that is contrary to Apple's official documentation, the entry-level 13-Inch "Late 2016" and "Mid-2017" models without the Touch Bar actually do have the SSD mounted on a small proprietary module, so future upgrades theoretically are possible.

from:

https://everymac.com/systems/apple/macbook_pro/macbook-pro-touch-bar-faq/macbook -pro-touch-bar-processor-ram-storage-upg…

Apple's policy is, "we do not sell parts." Apple will only replace, like-for-like, after a failure (no upgrades).