Instagram Comment Likes

Is there a panel here (marketplace) that provides likes for already existing comments for Instagram?

Yes, there are tons of such services although I don't recommend using such services. If you are planning to use such services, you can search in the marketplace as many sellers have listed their services there. Alternatively, you can post in the "Want to Buy" section if you have customized requirements from your seller/provider.

Yes, here sellers provide it. Check the marketplace and contact the seller.

plenty of panel sellers providing likes , tweets, accounts to buy
https://www.blackhatworld.com/forums/social-media.200/