getting engaged during the 3 weeks ideal yes or no. tried looking in shulchan aruch but no lekatchilah clearly
One may get engaged during the 3 weeks, and even to have a small engagement do for family and friends. This should not be done in the 9 days. However, it is permitted throughout the period to make an engagement official and for the parents to meet (vort). This can be done lechatchilah, because the modern-day engagement paves the way for the marriage. See Mishnah Berurah 551:16.