529 is a good option. It takes arguably ~$500 per month from birth through completion of college to fully fund a 529 with realistic expected returns. And that’s per kid.

So for sure 529 is a great option and definitely contribute to that. I have a 4 year old and a 2 year old and trust me I wish my relatives would all stop buying tons of toys my kid doesn’t need and just buy a cheap token toy they’re happy with and contribute rest to college fund. That’s what my brother and I do for each others’ kids. I buy a simple $20 toy my niece loves then stuff another $80 in the 529.

Not sure what state you’re in or they’re in, but I’m in Texas and so there’s no benefit to using a Texas specific plan here. As such I use the Utah plan my529.org which allows “gift links” that are easily usable for donating to someone else’s 529 plan. That way parents maintain control if that’s how you want it. Alternatively, you can set up a plan directly in the kids’ name.

Also, offer to pitch in for the nursery costs or just buy big ticket items on gift registry. The costs of setting up nursery + car seat + stroller + car seat bases + hospital bill + diapers + formula if/when it’s needed is…a lot. Our hospital bill was ~$7k per kid to bring them home, for example.

Beyond that, when the kid is old enough to have earned income (Eg 18-25), you could have kid set up Roth IRA and contribute to it and have discussions with kid about retirement planning and importance of saving early and offer to contribute more to Roth IRA after graduation if they continue to meet 401k savings targets for X% over Y years in order to give them a boost to saving for retirement.

Big ticket items like car at age 16 or paying for kids weddings or helping with down payment on a house are pretty impossibly expensive. But honestly 529 is best place to start