Can you eat normally whilst wearing expander braces?

With limitations. Whether you are referring to a palatal expander or braces that create arch expansion, there are specific food limitations that your orthodontist will review with you to prevent appliance breakage and/or trapping food debris under appliances that could lead to gingival inflammation and discomfort.
With some changes. Eating is the same, just need to avoid real sticky foods that could pull it off.