Read my post #118. I think Trump came out angry and gruff from the very start, probably hating being there, hating ABC for their slander against him, and despising being in the presence of Harris whom he would probably want to spit on, but it was either that or nothing as Harris had refused all other debate efforts, and it showed.
Trump never has angry rants at his rallies. But as I said, Trump is a poor public speaker, REMAINS a poor debater despite 3 years to improve himself, and missed opportunity after opportunity, most of it his fault. But Harris looked very bad too. Her childish facial mockery at times did not establish her as worthy presidential material capable of handling world issues.