A genealogy sub would probably be more helpful.

There are two places to find out whether your ancestor owned slaves.

First, the federal censuses contained slave schedules showing the number of slaves owned and their approximate age and gender. The Census records with slave schedules can be found at Ancestry.com and the National Archives. Check both the 1850 and 1860 censuses.

https://raogk.org/census-records/slave-schedule/#Researching_Slaveholders

https://raogk.org/census-records/

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Second, if you know the name of the Confederate soldier's father you could check the probate records of Pickens County because slaves would be mentioned in the probate records as property devolving to his heirs. Probate records usually have an index where you can search by last name.

https://raogk.org/southcarolina/pickens-county/#Pickens_County_South_Carolina_Courthouse_Records

Good luck.