Is a TDF a good choice for growing my money, in this case? I plan to use it for a house down payment and withdraw it in 5-7 years. I've been thinking of putting it in a 2030 or 2035 TDF. Should I go this route or just VTSAX and chill?
A target date fund on that horizon is going to be shifting its assets from stocks into bonds and TIPS, but is still going to have most of the volatility of VTSAX. If you're comfortable with the possibility of having negative return over 5 years, then you might as well VTSAX. If you need for the savings to grow, then you probably want less stock exposure than a future target date fund.
For reference, the historical 5-year return on US stocks is anywhere from +30% to -10%, annualized. Even over 10 years, you've got about 1-in-8 chance of losing money. I mean, the stock market is definitely the best way for most people to grow money over time, and the economy looks pretty good right now, but Time is definitely doing the heavy lifting, and almost no one ever forsees the event(s) that trigger crises. 5 years is pretty short term.
If you can be flexible on timing - put off the home purchase for a couple years if there happens to be a crash right at your target date, then a lot of volatility concerns fade. Of course, the middle of a crash is also when home prices will be lowest.
Vanguard's actual asset allocation on their TDFs is https://retirementplans.vanguard.com/VGApp/pe/pubeducation/investing/LTgoals/TargetRetirementFunds.jsf and there's a simple asset allocation - return calculator https://smartasset.com/investing/asset-allocation-calculator There's a bunch of them around, that was just the first one with error bars that came up for me, but it will give you a better sense of both how much and how variable the full equity vs the ~60/40 TDF will be. I like error bars. To my eye, it looks like there's not much difference in the 5-year median or 25th percentile performance, but a notable upside potential in the 75th percentile. That's why I say, if you're comfortable with the volatility, you might as well go all the way.