Our benefits are all things that wouldn't make sense to take away from a part-time employee to be honest.

We don't offer private health care currently, and every other benefit is a pretty direct link to how productive that employee is - technical books, better work environment etc.

For instance, we do a "wonder week" once a quarter to work on side projects/learning etc. To me, not letting a part-time employee do this would be to treat it as a kind of bonus, when instead we view it as an opportunity to explore ideas and skill up.

Benefits are a much smaller part of the package. Health coverage, for example, is nationally provided. For most of my employers, the main benefits would be vacation (which would be pro-rata), pension (ditto), and sick leave (effectively ditto, as it pays out based on actual salary). There are some much smaller fringe benefits (gym discounts, say) which would be given regardless of hours worked, but I'm not sure that would make a material difference.

For high-end jobs you might get private health coverage (or, under earlier tax regimes, a company car). I'm not sure how they are normally handled.