One of my students kindly sent me a link to this BBC article about the way Zelenskiy adapts what he talks about to his audiences:
https://www.bbc.co.uk/news/world-europe-60855280.amp
It seems to me that this adaptation flatters the different audiences as well as helping him achieve his aims of trying to garner support. For example, references to the Battle of Britain perhaps reminds British listeners of the time Britain stood up against tyranny. It also makes it seem earth shatteringly important because someone so far away refers to it. The same could be said of the mentions of "liberté, égalité, fraternité" for a French audience. They may be flattered by the reference.
I am also interested by the way he presents himself. He looks too busy to care about his appearance although he is probably quite mindful - he looks just "scruffy enough" (an interesting contract with Boris Johnson whose scruffiness is more over the top and seems contrived - there does not seem any purpose to Johnson's uncombed hair, for example). He appears approachable and has been seen taking selfies with ordinary Ukrainians so probably seems "one of us" despite having the elevated role. This contrasts with Vladimir Putin who is pictured at one end of a long table.