I need some "known clique size graph" dataset for an experiment . Is there any open source or site, where I can find them ?
I sadly don't know a source which provides that information. You generally can get alot of graphs from Network-Repository. There you can see the maximum degree m, so the graph can only have a clique of size at most m+1.
You then can manually insert a clique of size m+1 into the graph, and this clique then has to be at least as big as all other cliques.