We also use spacing to delineate sections. You can see there is quite a bit of space above each heading, making them easier to see.
You can also use horizontal lines if sections are important to you, or just create different notes.
It is a balance with the note title. We wanted the headings to be smaller than the note title.
You can change the overall text size in the settings of the app, but the difference in scale will likely be the same.