I don't think any such function exists. But if you can use gt.motifs to do this. For example, the following code gives simple implementation for finding the size of the maximum clique:

G = gt.price_network(100, 3, directed = False)

tot = 1

for i in range(1, G.num_vertices() + 1):
    g = gt.complete_graph(i)
    tot = gt.motifs(G, k = i, motif_list = [g, ])[1][0]
    print(i, tot)
    if tot == 0:
        break