Consider investing in TIPS for inflation protection after maxing out I Bonds. They have no purchase limit, and you can invest through a mutual fund or ETF.
How to Buy I Bonds (Series I Savings Bonds): Soup to Nuts
Series I savings bonds (I Bonds) are the best bonds you can buy at the moment. Follow this guide for a complete walkthrough from start to finish.
2019 Social Security COLA
A low Social Security COLA caused by low inflation is good for seniors.