I think that if Ferrari have the best car next season and the WDC is a battle between Lewis and Leclerc, I'd put my money on Hamilton. I'd base my bet on my feelings that Leclerc is, of the top drivers, most prone to make mistakes under pressure while Hamilton need pressure and inspiration to shine. But I also remember Valentino Rossi saying, when he was closing up on 40, something like "now I have to train twice as much, work twice as hard as before, just to keep up".
I'm not sure about Lewis needing pressure to shine. He has had title challenges that went to the wire and ones that didn't, and has won and lost a few of each. He won last race deciders in 2008 and 2014 but lost the ones in 2007, 2010 (outside chance), 2016 and 2021. He won before the last race(s) in 2015, 2017, 2018, 2019 and 2020 but didn't have to face the final race jitters in those years. My point, though, is that being under high pressure from a rival hasn't brought out a better, more inspired version of Lewis as is being suggested. If it's close for the title between the two Ferrari drivers, he has more experience and that will benefit him perhaps but he is not remarkably better in those sort of situations.