So I came to thailand with the thailand plus, now that I am here, I am wondering if I can extend my visa at the local immigration office. There were a lot of requirements to get here, PCR Test, Insurance, etc. First off, I still need the immigration form, a photo within 6 months, the fee, but do I need to show proof of insurance for my extended stay, since my original insurance only covered my first 30 days here? Is there anything else that I need?

Do not need insurance.

Just apply for extension

Since you talk about a 30-day initial stay, I assume you are talking about a visa exempt entry, not a visa on arrival. I further assume that you are not entering with a transit visa. This is important as the permission to stay from a (15 day) visa on arrival or (30 day) transit visa are not eligible for normal extensions. Anyway, no insurance is need to extend the permission to stay on a visa exempt entry.

Thank you guys, and yes you are correct I meant that