Renovate currently has the ability to update .pre-commit-config.yaml if the behaviour is opted into. At the moment renovate is only updating the declared rev (repo tag) dependencies.
It would be nice if renovate could also update any additional_dependencies if present, applying the supplied renovate configuration around pinning etc.
For the given example .pre-commit-config.yaml file in this repository if ran with renovate today the rev for the prettier repo would be updated to v3.0.0-alpha.6 however the additional_dependencies of prettier would remain at v3.0.0-alpha.5 giving an inconcistency, and eslint-config-prettier would be unchanged.
Renovate would update the additional_dependencies to that prettier was updated to v3.0.0-alpha.6 and eslint-config-prettier was updated to @v8.7.0.
As pre-commit hooks can be in a varianty of languages correctly identifying the upstream package manager of additional_dependencies will probably necessitate retrieving the .pre-commit-hooks.yaml file from the referenced repo to ascertain the language attribute.