Erik Kostson
Ansys Employee

Solid186 you can simply get without any apdl command snippets, and just by setting in the mesh details, defaults, element order, and set it to quadratic.

It is also the default element used by the mesher (if we do not change anything here and leave it to program default) for 3D solid parts.

So the command snippet I show say: et,matid,beam4 - in this case to change a beam188 element which is the default for line bodies, to a legacy beam4 element - so no need to use snippets on the elements that we already get by default (solid186) or by changing the element order setting (mentioned for getting shell281 elements).
All the best