In Jainism, a diksha (initiation) is given by a qualified guru (an Acharya or a senior monk/nun) who has the proper authority in the lineage. A lady sadhvi is a respected renunciant, but the act of giving diksha to another person is typically performed by a senior guru within the tradition.

• In the Digambar tradition, full monk-diksha (muni) is traditionally for men; women take Aryika-diksha (a high-status nun’s initiation) instead. This reflects how the path for women is organized in Digambar lineage. ( jainknowledge.com)
• In the Shvetambar tradition, women can take diksha and become sadhvis (nuns), and they generally participate in the same specialized initiations within their lineages; the exact rite may vary by sub-tradition and guru lineages. ( jainknowledge.com)

If you want, I can point you to a JainKnowledge page for more detail specific to Digambar or Shvetambar practices.