In Jain Dharma, yes—a person from any background can स्वीकार/accept Jainism by sincerely taking refuge in the Jain way of life: ahimsa, satya, aparigraha, and right conduct. There is no requirement to be born Jain.

However, changing your religion in official documents is a civil/legal process, not a religious one. Jainism itself does not give a separate “official document” rule for this.

So, in simple words:

• Spiritually: yes, you can become Jain.
• Officially in documents: that depends on the government procedure where you live.

If you truly wish to follow Jain Dharma, you may begin by accepting the five main vows as far as possible, living with non-violence, and studying the Jain path sincerely.