Jesus tells us to store up our treasures in heaven, that if we store up on earth, what we gather could be destroyed or stolen. Many advocate stocking up in preparation for the times to come. I think you should only do that if you are sure you are directed to by the Lord. Otherwise, we have only the biblical mandate to store our treasures in heaven instead of on earth.
Many quote the Joseph story as teaching us to store up. But that isn’t a command to us, it’s a story showing us that we can trust God is already ahead preparing for us. “But God sent me ahead of you to preserve for you a remnant on earth and to save your lives by a great deliverance.” (Genesis 45:7) It’s a story of God providing for his remnant.
I’m not against having basic supplies on hand. If there is a natural disaster, power outages, quarantines, etc., it will be a blessing to you and to those you share it with. If you do stock up, you have a biblical command to share it with others. And what worries me is that when word gets out that you have food and others are desperate, what will they do to get at your food?
We can instead rely on the Lord to provide for us. We have a few requirements: seek Him and His righteousness, give, ask.
How do we store treasures in heaven? Give to the poor. Give to needy Christians. We are told especially to give to those in need in the Body of Christ. If you need help finding truly needy Christians, try Heaven’s Family which helps needy Christians, mostly in the third world. They give 100% of your money to the project you choose. Give to orphans, widows, persecuted Christians…
Store up those treasures and from your treasury you will be provided when you need it.