Hi @mayank0928,
I am afraid this is not supported yet in on premise AEM 6.5.x, and 6.5.15 is not an exception. I am assuming you are referring to below documentation that is describing offset and limit parameters:
Above documentation is AEM as a Cloud Service version, and there is no feature parity between on premise an cloud version of AEM. Base on AEM as a Cloud Service release notes, offset and limit parameters have been added in the latest AEM as a Cloud Service, as part of prerelesae feature.
Summarizing, if you want to use offset and limit parameters in AEM 6.5.x you will need to wait until this will be supported. You can follow release notes and SP roadmap, to get idea when potentially this you could be delivered. Additionally you can contact Adobe Customer Success Manager/Engineer that is dedicated to your project, and ask if he/she can provide you specific date, SP version that will include this feature.