Oh, that's interesting. I do use TripIt pro but store PDFs of all my docs under a Trip xx_ under collections in Apple's 'Books' app.
I was going to suggest to start a thread 'Help me with ...' but if it was something like eSIMS, you'd get all sorts of people jumping in with the latest & greatest "Really cheap 50Gb from Hungarian Telecom offered through their Polish site..." and 10 others telling you how to do it 10 different ways. I can only just say I can just manage eSIMS but still have problems with them - like today.
Best if someone can show you in person. But you could try to start a thread for your particular phone type and destination BUT having said all that, I have thought KOLET is very good and simple. Great instructions. Search KOLET on AFF and you'll find a 'referral' thread & go from there.
But as far as docs are concerned, I get everything as a PDF - either scan it myself - passport page, doctors letter, drivers licence etc or e-mail downloads such as vax certificates, travel insurance, rail tickets, air itineraries, anything, and save it to the Books app in iPhone, then organise into each trip. I also carry a folder of hardcopies of the most important stuff, but I also know its on the phone at any time.