Refer to the solution in this thread for details on the angles required for orientation:
https://community.ptc.com/t5/3D-Part-Assembly-Design/Iso-views-based-on-Default-Orientation/m-p/924392
See my post with the values to get Isometric projection relative to current view; TLDR
ISOMETRIC (proportion of the three sides is 1:1:1):
The horiz. angle should be the ArcSin of (1/(Sqrt(3))) = 35.26439 degrees
This is equal to ArcSin of Tan(30).
Due to rounding errors in Pro/E you can better use the value: 35.26379
Orient your model in an orthographic view with the desired axis orientation. Use view dynamic orient to put the model in ISO view and then save the view.
