I have set up a new Ghost install and am using the free London theme.
I would like to make some tweaks to this theme. I'm new to Ghost.
Should I just directly make edits to the local files, or is there a more sustainable way to do this, like child themes in WordPress?
If I directly edit the local theme files, what happens when the theme and/or Ghost are updated? Or do things work differently in Ghost?
As far as I know, there is no "child theme" for Ghost.
I think your best bet is to create a fork of the Github repo and then edit the theme files directly in your fork.
If the theme is updated, then you can merge the changes to your fork.
If Ghost is updated, then it depends on the nature of the changes whether or not the theme has to be updated as well. But in that case hopefully the original author also updates the theme and then you can merge into your fork again (or if not, you can update your fork and push the changes back as a PR).