I assume you are referring to modeling light propagation in an SMF28e fiber terminated APC with nonsequential mode in Zemax. Yes, it is somewhat reliable believe it or not.

you can use another software tool such as Optisystem

You can design a code by matlab to analyze the optical beam profile or used a CCD.

With non-sequential ray tracing code of ZEMAX, you may analyze rays propoagating within the fiber and exiting the tip.

I agree with Mudhafar Hussein Ali

ZEMAX can simulate mode field diameter(MFD), Encircled energy and some other parameters

I had found that Zemax can simulate a beam after fiber like a ray bunch form point source placed at some distance from aperture that restricts the beam diameter. You can define intensity distribution through beam profile.

To simulate beam propagation after angle cleawed fiber you can for example use some skewed glass plate.

The attached is two cases: 1 - flat fiber tip (glass to air border), 2 skewed tip

In that model the NA in object space 0.1 is set, distance of point source to appeture is 0.05 mm.