There are some notes which sound out of tune, but I’m not convinced its intentional and would guess it’s more likely the result of one or more strings not being tuned correctly or going slightly out-of-tune (as guitar strings are prone to do).
When you asked about tuning in a guitar sense, that means tuning strings to another note, usually by lowering the tension of one or more strings (often by one tone), rather than using different tuning systems such as just intonation, Pythagorean tuning, well temperament and so on. In this sense, I don’t think the guitar is using an alternate tuning.
I also don’t think the music in the song is using a different musical tuning system (deliberately using notes that are sharp or flat) because:
a) He’s playing a guitar, which is built for equal temperament, and if you were to play in a different tuning system, you’d have to move all the frets of the guitar slightly, which is quite an undertaking.
b) Using any other tuning system (just intonation, Pythagorian, well temperament etc) is extremely obscure in the modern world and almost certainly beyond the ken of rock/popular musicians.
Also, chromatic in the musical sense means using the using the chromatic scale, which uses all twelve semitones in the octave. There is no use of the chromatic scale in the solo - it uses the standard diatonic major scale.