The tv-adjust-heading-level variable allows the level of headings to be adjusted. It is interpreted as a positive or negative number (e.g. "2" or "-3") that is added to the heading level for display.
Note that if the resulting heading level is less than 1 then level 1 is used instead. This means that specfiying a large negative adjustment factor will reset all headings to display as level 1. Similarly, heading levels larger than 6 are clamped to the maximum HTML heading level of 6.