I partially agree with @Mentalo, the ideal kind of lenses for the X-PRO3 are the primes.
But I think that is same situation an all-round zoom is more flexible.
The question is that this zoom must have a good quality and a portability adapted to user needs.
In my opinion the options are as follow.
Fujinon XF 18-55/f2.8-4 or XF 16-55/f2.8
I own both lenses.
The 18-55 is a good lens, small and light so very portable. It has the stabilization and the only caveat is that it isn't weather resistant.
The 16-55 is a fantastic lens but is huge and heavy. It isn't stabilized but it is, IMHO, a perfect all around lens.
Fujinon XF90mmF2 R LM WR if you need a telephoto lens.
Perhaps you are thinking to a ultra-wide-angle lens, in this case you can evaluate the Laowa 10/f4 Cookie that is really small, not perfect but with a reasonable quality.