The Plan Forecast page is only available on the desktop web app at https://app.monarchmoney.com/plan?timeframe=monthly
This view is similar to the monthly Plan Budget page but it shows all 12-months of the current year in a grid so you can quickly edit multiple monthly budgets across all categories.
This can be particularly helpful if you want to enter a known future expense such as a big vacation, a large bill or seasonal expenses like holiday gifts or taxes.
There is a drop down to switch the view to show years instead of months and then you can view up to 10 years in 1-year intervals across all categories. Yearly budgets are simply the sum of all 12 monthly budgets so you can't edit the yearly budget but if you edit a month in that year it will change the overall yearly budget.