@wm,
It seems to be working fine. Please check this sample project in react-native, in which font-size of axisX labels is set to 25.
Can you kindly share sample project reproducing the issue you are facing along with the browser / steps that you used for the same, so that we can run it at our end, understand the issue better and help you out?
—
Vishwas R
Team CanvasJS