Answer

No. In Jain Dharma, a person who attains omniscience — Keval Jñān — does not automatically become a Tirthankara.

Every Tirthankara is a Kevali, but every Kevali is not a Tirthankara.

Explanation

A Kevali is a soul who has destroyed the four destructive karmas and attained perfect, infinite knowledge.

A Tirthankara is a special kind of Kevali who establishes the Tirth — the fourfold Jain community:

• Monks
• Nuns
• Laymen
• Laywomen

To become a Tirthankara, the soul must have previously bound a special karma called Tirthankara-nāma-karma. Without this specific karma, even an omniscient Kevali does not become a Tirthankara.

Spiritual Understanding

This shows that omniscience is the supreme state of knowledge, but the role of a Tirthankara is a special world-guiding role. A Tirthankara not only realizes liberation personally but also re-establishes the path of Dharma for others.

Takeaway

Keval Jñān makes one omniscient, but Tirthankara-nāma-karma makes one a Tirthankara.