I am not with Laminar Research; just a flight simmer.
Have a look at the following link at https://www.x-plane.com/kb/x-plane-11-system-requirements/ for the system requirements. Serious flight simmers go for a purpose built Windows based PC using specifications equal to or better than the recommended specifications.
In building a purpose built machine you can upgrade components as and when necessary and when affordable. Here in Australia a Mac system will cost an arm and a leg to purchase whereas a PC will not cost as much.
One issue you need to have is good cooling on the CPU and around the graphics card as a considerable amount of heat is generated. Does your proposed unit have any cooling? Bad or no cooling will contribute to the system crashing during a flight.
I am of the opinion that the graphics card is the weakest part for your planned system. Have another look at the recommended specifications. Also consider a NVidia graphics card instead of an AMD or clone card. NVidia has been known to give you a better performance. From my readings in this forum this is particularly so with a MAC.