When I'm staying for a few days in a different part of my country (Italy) I end up switching to the local phrase construction pattern if it's notably different from my native one. Accent not so much, I guess it takes quite a long time. Words are easy to swap (like truck/lorry in English) and pronunciation quite easy too (change of vowel sounds in my case.) BTW, none of this involves speaking dialects, it's all Italian with regional differences that everybody understand.

Aren't [geographically] localised linguistic characteristics (different words, different pronunciation) pretty much the definition of "dialects"?

Not in Italy. Dialects here are languages. They basically belong to the same family of Italian but I won't be able to understand a dialect 50 km from where I live if speakers don't want to italianize it a little. What I was writing about is standard Italian with regional inflections in accent, phonetic, dictionary and syntax but still understandable by any Italian speaker.

Ah, interesting, thank you.

Yeah it's "accommodation". But people also do the other thing where they repeat what you say and honestly I think they're just relishing this other similar sound they enjoy.

True! Almost all of my extended family lives in South Louisiana and many have quite thick Cajun accents. When I spend too much time around them, I end up sounding a bit different when I get home.