Analog Fuji look
In my opinion there are two factors in the Fuji X Trans rendition. The first, as stated by others, is colour. May I add that I don't like OOC jpegs, as I find the colour over vivid and over saturated. But that's just one click to correct. Otherwise, both the skin rendition and the natural greens are excellent: my old digital files have a metallic green which nel X-Trans never produces (and you can expect it, with all those green.reading sensors…)
The second factor is given by the smooth transition of tones. It is preserved because, having no AA filter, you don't need strong USM or strong local contrast to have a sharp image. It takes time to find the right formula for a light USM to guarantee both apparent sharpness and sweetness of passages, but it's worth the effort, I find (my formula is Nik presharpner at 35%, with zero sharpness in all the previous passages).