After model(s) have successfully been generated, it is up to the engineer to compare and contrast the different designs, considering things like:
Sustainability, manufacturing capability/capacity, supply chains, scaling, product lifecycle, customer feedback, branding, and more!
Once a design is decided upon, the engineer then converts the design into a usable CAD model, which can take on a variety of different formats:
Solid-Body Models, the most common for traditional engineering
Mesh Models, typically used for 3D-Printing, animation, etc.
Surface/Form Models, typically used for artistic design/engineering
If there are customer/design requirements or constraints beyond the scope of product performance
Constraints can include superficial constraints such as certain desired aesthetics, branding, etc., and/or can include engineering constraints not captured/accounted for by generative design (ex: fatigue)
Once a design is generated & modified, it is often necessary/essentially to "prove-out" the design via FEA and/or other simulation methods, to verify/validate the performance of the product
This is especially crucial is any manual adjustments are made to a generatively-designed model, as the adjustment could easily induce stress risers, weak points, etc.