I am trying to make a Go enrichment analysis via gene list containing 30 genes, GO analysis was performed on GO online tool. the results were reported as a txt. format file contained a P value, Fold enrichment . can I plot the value against Fold enrichment to generate a volcano plot?
You certainly can.
I imagine such a plot could be a bit misleading, because GO categories may be related to each other and you may get a lot of enriched categories, but all related to each other and the same set of genes being responsible for all - you could remove the redundancy somehow, e.g., with Revigo.