Tax sales of real property get recorded with other land deeds in the appropriate local office (usually the county recorder, but not always). However using the grantor and grantee indexes to land records will not locate these deeds.
That’s because the grantor on the tax deed usually is not the owner who failed to pay their taxes. It’s often the county sheriff or another county official. The person who did not pay taxes and had the property taken from him because of that is not the owner. That’s why they are not the grantor on the property–they don’t have the title to transfer.
The deed will be in the grantee index under the name of the purchaser of the property. That’s another name the researcher probably does not know. There is one place to search in the local records for the name of the property owner whose property was sold for non-payment of taxes: local court records. They may appear in a lawsuit as a defendant in the legal action that took place before the property was actually sold for non-payment.
Their name may also appear in newspaper notices as well.