This was published earlier today:
According to it, the patch can be installed as in previous versions:
Patches are made available as tarball-style archives that may be unpacked into the products folder of a buildout installation and as Python packages that may be installed by editing a buildout configuration file and running buildout. Patching is generally easy and quick to accomplish.
But we have seen that this 'products' folder is not available in Plone 5.2 with python 3.
Can anyone confirm that this method of installing the patch is available or we will need to run buildout?