You can edit prices for a single item using the Walmart Seller app. However, you can’t automate pricing through the app.  

You can automate your pricing through the Repricer and set up a Repricer strategy using the desktop version of Seller Center.

Additionally, you can set up various strategies to offer your customers the most competitive price. For example, you can set up the Buy Box Strategy, which automatically adjusts prices while maintaining the same meet or beat margin.