If I understand correctly. This is a window:
From a bedroom AND there is NO other egress? As additonal exits and their size will influence the outcome of this. Do your Approved plans inc. Screened in Porch?
If the window in question is the only means of egress, I would generally NOT like to see that nor would most of your local Building officials.
Most answers over the years in different jurisdictions have said…
Patio COVER - OK, but once you are screening or closing the Patio in and prohibiting/limiting exit… not generally advised OR allowed. Most codes indicate exit to EXTERIOR (some say alley or similar as well)
If there is another point of egress, such as an exterior door or window that is the proper size for egress, the screened in porch is likely OK. As mentioned, consulting with your local building and safety, your contractor as well as voicing your concerns to whomever is drafting your plans… you’ll get there!!
This goes without saying, as I’m sure you know. In the end, it’s for you and yours safety!