Yes, We-retail is the sample website provided with AEM and you can copy it to create custom pages. You can create a new folder(/apps/weretail-copy) and copy the clientlibs/components from "/apps/weretail"
Similarly, templates/policies/cloudconfigs reside under "/conf/we-retail/settings" directory, you can copy and from here and create templates using we-retail.
Lastly, if the instance is started with nosamplecontent runmode, you can download if from [1]
[1] Releases · Adobe-Marketing-Cloud/aem-sample-we-retail · GitHub