How can I use a custom value in WIQL query? (Azure Devops)

Question

Good morning,

I have created a custom fields to specify the number of days to review a task. And the next step, is create a query with this logic: @today + customField < endOfCurrentIteration

I don't know how can I get the last day of the currentIteration and it marks an error when I try something like this: "[System.CreatedDate] > @today-Custom.Days"

Thanks