The highest temp will be whatever you have your water heater set to. You get straight hot water when using cycles other than the normal eco cycle (the normal eco cycle uses virtually all cold water).

Keep in mind that with a washer has no internal water heater, your hot water might be cooling a few degrees between the house water heater and your washer, depending on how far apart they are.

The mass of the machine parts and the clothes also pick up some of the heat. Filling one of my agitator toploader washers (not a Speed Queen) with 115°F water, which is what the auto temp control takes in for Warm, results in approx 105°F to 108°F when fill is finished.

I have a speed queen front load set (actually two of them) and have our hot water heTer set at 150. When I select got it gives me true hot not dumbed down temps like most machines do now a days. I was nervous about getting machines without an internal heater but it was a good choice. I know when I put something in that machine it will get 100% clean and not take hours to do so like other front load machines.

Expanding a bit on the previous comments, SQs do not have programmed electronic Automatic Temperature Controls (ATC), dumbed down or otherwise. Instead, they use a simple mixing valve for water temperatures. Except for the Normal/Eco cycle, "hot" is whatever arrives from the water heater, "warm" is supposed to be a 50/50 mix of the hot and cold water feeds, and "cold" is whatever comes in the cold water line. (I say warm "is supposed to be" a 50/50 mix because dadoes has previously pointed out that the hot intake pipe may have a restricter that makes it narrower than the cold intake, a practice seen on other brands and one that puts a downward skew on the temperature for warm washes.)

On both TL and FL SQ models, the "Normal/Eco" program apparently was designed solely for Energy Star testing. According to what SQ has published (confirming what littlegreeny says above), that cycle uses "88% to 100% cold water" no matter what temperature selection is chosen on the control panel.

Of course, without an on board water-heater and recirculation pumps, the "tap hot" water temperature will be less than the water heater setting --- for the reasons listed by Cavimum and dadoes --- and will decline further over the course of the wash cycle. The decline seems to be in line with dadoes's sugestion above according to actual measurements by Jeffrey Caban in this thread from a couple of years ago:

https://www.houzz.com/discussions/5193795/my-three-weeks-and-counting-with-a-speed-queen-fl-afne9bsp113tw01#n=37

I left a question on that old thread, thus resurrecting it.