The jump in benefits, the biggest in the program’s history, comes after a revision of the initiative’s nutrition standards that supporters say will reduce hunger and better reflect how Americans eat. Under rules to be announced on Monday and put in place in October, average benefits will rise more than 25 percent from prepandemic levels. All 42 million people in the program will receive additional aid. The move does not require congressional approval, and unlike the large pandemic-era expansions, which are starting to expire, the changes are intended to last.