Yes, but it depends either on the configuration of your system or your ability to craft some custom web script / URL calls. Every Alfresco installation has a default action called "export" which can be called by any user. This action can create a downloadable ZIP-like file (ACP = Alfresco Content Package), which can - with potentially no or only minor adaptions - be imported into another Alfresco system using a similar "import" action.
Unfortunately, a default Alfresco installation does not provide a UI action to trigger either the "export" nor "import" actions. So unless your system has been configured with some customisations, e.g. by adding a 3rd-party module to provide access to those actions or having some custom configuration to enable this, you are forced to craft web script calls using any kind of HTTP / ReST client (e.g. cURL). Such a call essentially needs to "fake" the submission of a form for the action, including the necessary action parameters as specially prepared form parameters.
"00060014 Wrapped Exception (with status template): 00060168 An error occurred while processing the template 'When calling macro \"formDefJSON\", required parameter \"form\" (parameter #1) was specified, but had null/missing value.\n\nTip: If the parameter value expression on the caller side is known to be legally null/missing, you may want to specify a default value for it with the \"!\" operator, like paramValue!defaultValue.\n\nThe failing instruction:\n==> @formDefLib.formDefJSON form=form [in template \"org/alfresco/repository/forms/formdefinition.post.json.ftl\" at line 2, column 1]'.
What should be the value of the "fields" parameter? How can I specify which site should it export?