Buying individual bonds and holding to maturity is a far better strategy.
Yes, when you buy bonds and hold them till maturity, you can more closely estimate how much your loss is in real terms. Basically, it’s roughly the yield minus inflation, which is now estimated to be negative for nearly all government bonds, and even negative for many corporates. But when you buy bond funds, there is no way to determine how much you will lose, because that depends on others (if they sell shares in the fund, the fund manager has to sell bonds at a loss, perhaps not only the yield minus inflation loss, but also a [permanent] capital loss by selling the bond under par).
I’m not sure what retirees are doing with their bond portion nowadays. If you have a 60/40 portfolio, that’s a LOT of fixed income you need to find! The only bonds I own right now are I-bonds (with real returns between 0 and 3.4%).