Extract all field names from an SObject

public class ExtractFields {
   public static void queryAllFields(String objTypeName) {
        Schema.DescribeSObjectResult[] descResult = 
            Schema.describeSObjects(new String[]{objTypeName});
        
        Map<String, Schema.SObjectField> fsMap = descResult[0].fields.getMap();
        List<String> fieldNames = new List<String>(fsMap.keySet());
        for(String f:fieldNames){
            System.debug(f);
        }

String queryString = 'SELECT '+String.join(fieldNames, ',')+' FROM '+objTypeName+' LIMIT 1';
        SObject obj = Database.query(queryString);
        
        System.debug(obj);
    }
}

In Execute Method: Call ExtractFields.queryAllFields(Account);