Because it's a secret ballot, vote returns by race/ethnicity, gender, or other demographics are only discoverable via survey. See my political survey guide for sources.
For a good explanation of the difficulties and complexities involved in collecting, cleaning, and interpreting precinct boundaries, see Redistricting Data Hub's explanation as well as Amos, B., Gerontakis, S. & McDonald, M. United States Precinct Boundaries and Statewide Partisan Election Results. Sci Data 11, 1173 (2024). https://doi.org/10.1038/s41597-024-04024-2