You can certainly find gnarly trails even on XC trails, but if it’s normal trails and not an extreme area, those are brief sections with routes around. Regardless, the rule always stands . . . ‘when in doubt, dismount’. Walk it in those brief sections and get back on to return to normal trail riding.
A lot of the UCI stuff is manmade sections to test them. If someone made something manmade like that in a section there is typically a ride around option