I don't worry about humidity unless it's below 20 percent.
You will be fine at 27 percent.
For hatching I try to jump my humidity to 70 plus.
Not sure what incubator you have but most humidity gauges are off in them.
I just did a hatch. Had 3 incubators running. All in same room. The...
Dry incubatiom for me is I don't add any water unless my humidity goes below 20 percent. Rarely does it ever. But if it does I just add a tablespoon or so of water.
When day 18 for chicken eggs comes about I raise humidity to 70 to 80 percent for hatch.
Most that dry incubate try for 30 to 40...
I dry incubate in my styros.
usually I just bring humidity up to 75 to 80 per entry on day 18 when I lockdown my chicken eggs.
no gradual increase I just jump it up.
good luck on your hatch this round.