Yes you can—we support
pstricks via XeLaTeX. If you have:
in your document preamble, it should automatically choose to build with XeLaTeX, and it should all just work as normal.
If we're not automatically picking up the need to use XeLaTeX, you can click the gear icon in the top right of the editor and choose XeLaTeX under 'advanced build options'.
If you'd like to try an example to get you started with pstricks, choose one from the list below:
All the examples can be opened as templates in the Overleaf editor for free editing online.