Nah-uh, not usually. The TVA contracts, and the wall may do a degree, but if you consciously flex the abdominals during any movement, it makes it more difficult (that is, when it's a core movement). For squats, deadlifts, and OHP, you really should be breathing normally.
Everything I've seen has shown the abdominal "brace", as McGill calls it, to be better for protecting the lower back (the prime focus of either technique), as well as avoiding any risk of hemorrhaging. Yes, the blood pressure rising may not be an issue for most, but it's something to think about. Plus, I feel better flexing the abs (no pushing out or sucking in - people do it all wrong. A simple flex is fine) while breathing steadily for my sets.