I tried to make a Dem gerrymander in Ohio with 8 Biden seats vs only 7 Trump seats. Albeit OH-02 is only Biden+1 but still.
Indeed, back in 2018, when 538 released its "Atlas of Redistricting," it found that in OH, the most pro-D gerrymander they could come up with at the time was 8D-8R (with three swing seats - two of them R-leaning and one of them D-leaning). This goes to show that political geography mostly favors Republicans in OH, but I still think that a map drawn by a truly independent commission and/or a court-appointed special master would most likely be 8R-7D.