Most 529 college savings plans and 401(k) company retirement plans offer a pretty broad range of U.S. stock mutual funds. There are large-cap funds, small-cap funds, value and growth funds, and even sometimes actively managed versus passively managed funds.
When it comes to bond funds, however, many such plans limit you to just one fund that tracks a single bond index – typically, the Bloomberg Barclays Aggregate Bond Index, also known as the Agg. This is backward. They should be providing more choices for bond funds than for stock funds.