Hi!
Yes, you can upgrade the current 128 GB SSD to a larger one. You will need to back up your data and also get an enclosure to make the transfer easier afterwards [*]. Here’s what you’ll need:
* [https://amzn.to/2BtZ1Rx|Transcend JetDrive]
* [https://amzn.to/2GnUDZW|Aura Pro X/ Xb SSD]
There are other models of drives that you can use, but you need to make sure that they are compatible with Apple MacBooks.
[quote][*] There are a few different ways you can do this:[/quote]
[quote]First create an OS installer thumb drive following this guide: How to create a bootable macOS High Sierra installer drive This will allow you to install a fresh OS on the new drive.
As far as your data you could reuse your old SSD using the special case you can get with either SSD supplier or just make a full backup onto an external drive using TimeMachine then restore onto your new drive.
[from @danj ‘s post [post|436114]][/quote]