There are 4 different ways that UPSes are designed to handle "high voltage"
The first is 208volt only. This is the most common type of high voltage system, since nearly all server rooms in commercial facilities have this power pre-wired. The UPSes input this 208v and then output 208v.
The second is 220,230,240v. These are primariliy for international use. UPSes using this power format nearly always have IEC type plugs and ports. Most of the units are auto-sensing for that range. Unfortunately they do not output 208v. If you plug these into 208volt, they will output 220,230 or 240v. So dont buy these if you have 208volt power.
The third type is 208/240v. Here the UPS can be configured to accept 208v or 240v. As I mentioned, 208v is common high voltage for commercial facilities, but 240volt is common high voltage in non commercial facilities and in your home (think your dryer). Most newer APC units are setup 208/240volt. In these units, the plugs and ports are NEMA twistlocks.
The final type is "universal high voltage." In these systems, 208v, 220, 230, 240 are accepted. The UPS auto-senses the voltage. This format is found in most Tripplite and Powerware systems.
None of these systems step up or step down the power... they output the same as the input.
Below lists some common units for each type.