I have been using the Concave Hull plugin in QGIS & the Shared Nearest Neighbor Clustering feature.
I am having issues with this plugin, each time I choose the option of "Number of Neighbours" it doesn't seem to work.
This is the same issue DrottTom explains in his post here,
clusteringtool in the processing toolbox. Then create concave hulls using theconcave hulls (k-nearest neighbor)algorithm, which allows you to specify a grouping field. – csk Jun 21 '19 at 20:37