In practice, VE often starts when bids come in over budget. The GC asks each sub for ideas and the savings each idea gives.
A flooring sub might offer a different tile from another maker. An electrical sub might offer a different conduit type where the code allows.
List each idea as a separate line with its own deduct. Say what changes in performance, warranty or appearance. The architect and owner decide.
Do not include a VE idea in your base bid. Price what the documents show, then offer the idea as a voluntary alternate.