It's a tricky one. I've got the same computer. When I looked at the OWC offerings, they all had some awful tricky tech shit you had to figure out in order to make them work right. At the time, about a year ago, it was very much NOT a "drop it in" replacement scenario. I gave up because of the complexity.
I just use external SSD drives for samples, and have offloaded as much as I can from my main internal drive to Google Drive that I'm not using regularly. That keeps me at least 100GB free on the main drive, which seems to be fine for my purposes.
You might look into the incredible CleanMyMac software - it's about $50/year but it does an amazing job of deleting old log files and cleaning up system junk and keeping your Mac running well. I swear by it.
Good luck!
Mike