A tax refund is not a gift from the government. It's your own money that you sent to the government during the year, and they send it back to you when you file your tax return.
If you want to get a bigger refund, you and your wife can give new W-4 forms to your employers to increase the amount of federal income tax that is withheld from your pay. But if you do that you are just sending more of your own money to the IRS. They hold it all year, and send the excess back to you at the end of the year as a big refund. They don't pay you interest on the money they hold.
You can use the Tax Withholding Estimator on the IRS web site to figure out what you and your wife should each put on the W-4 forms that you give to your employers. It will show you how to adjust your withholding to get the approximate refund amount that you want.
But you'd be better off taking the money out of your pay yourself and putting it in a savings account that pays interest. At the end of the year you can give yourselves a big refund from the savings account, and you will have a little extra because you will have earned some interest.
