Z.D. Laltanpuia Not sure exactly what your end result is ... so, given some polygon ( usually a rectangle ) of your AOI (Area of Interest ) that contains your landslide polygons. Knowing what GIS you are using would be helpful if you want a detailed response. A simplified hand drawn sketch or mockup from Powerpoint would be helpful.

1. Generate an AOI polygon using vector tools, one can simply create a new layer and draw it in an edit session, or use coordinate values for the polygon points. Or you can use a buffer tool on the landslide poygons using a suitable distance, then feed that to a vector tool for Minimum Bounding Geometry ( usually 'envelope' https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/minimum-bounding-geometry.htm#I_ESRI_TOOLILLUSTRATION_53B37640EA3940DCAFA38DBB90AEF917 ), or use the watershed boundaries or whatever best represents you AOI . QGIS nad other software have similar tools: https://docs.qgis.org/3.34/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html#bounding-boxes or https://docs.qgis.org/3.34/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html#oriented-minimum-bounding-box

If you wanted a set of polygons for the AOI that had the simple categories of 'Landslide' and 'Not Landslide', one would use one of the vector Boolean operations tool - in this simple case, to punch holes corresponding to the landslide polygons into the the AOI polygon. In ArcGIS, https://desktop.arcgis.com/en/arcmap/latest/tools/analysis-toolbox/erase.htm ( QGIS has similar tools ).

If your desired result is more complicated, like your AOI has a base layer of something with attributes like surface rock types or land cover, and /or the landslides need to be subdivided according to those features, all along with preserving the various attributes, it involves a sequence of those boolean operations.

All this can be 'automated' or handled programmatically, depending on the degree of automation needed. That can be done with various tools like Model Builder or via Python.

Michael John Patrick Thanks a lot for your detailed and insightful answers. I really appreciate it. I am working on ArcGIS 10.8 version.