Would mixing 85% formic acid and 32% sulphuric acid be harmful?

Formic acid is what makes an ant bite hurt so much. (Formicus is a species of ants from which it was first extracted.) Sulfuric acid is commony called battery acid: it will eat holes in your clothes if you just walk past it.

Concentrated sulfuric acid is a strong dehydrating agent. In a solution it dehydrates formic acid to release carbon monoxide. You will want to wear appropriate protective clothing and work in a vent hood.

Always fully research the chemistry of an experiment before you do anything. For instance I once dropped a silver ring into Windex to clean it. I didn't know that ammonia dissolves silver. I also didn't know that ammonia-silver is an explosive when it dries out.