If you consider the era, type of music, and the title (Lucy in the Sky with Diamonds is the correct title) I'd say the evidence points in that direction.

Although Lennon denied this, he admitted he was inspired by LSD. However he has a good reason to deny this: to avoid the radio ban.

Perhaps we will never know for sure. We do know for sure it was perceived as such.

[1] https://en.m.wikipedia.org/wiki/Lucy_in_the_Sky_with_Diamond...