A header here would surely transfer a load, straight down!
Headers over windows and doors transfer loads to each side and not into the opening.
Headers (same word, different use!) off certain platforms should only be made when one can safely land, like into water!
When I went out onto this porch it reminded me of the beach.
As a child we would rent a house on the Chesapeake Bay.
We called it "the beach" because sand had been trucked into an alcove, which was netted off against crabs and sea nettles for swimming.
We rented the same house every year!
The porch looked just like this!
My mother would say the same thing as soon as we arrived, "You and your brother stay away from the screen on the porch!"
She didn't want us playing and taking a header through the screen, off the porch, and into the yard.
I could almost hear her voice here!
On the right the drop is only about 3'. On the left, though, it's over 8'!
Screens do not handle much weight.
This porch has been like this for a long time!
Can you see that lonely receptacle midway on the long wall?
At least it's safely installed, covered properly, grounded and protected by a GFI.
Okay, maybe none of that is true.
In fact it had fried a long, long time ago. And it should have! It's an old metal box, likely from the 60s, and really very dangerous!
Nothing about this receptacle is safe or correctly done.
And there is not much safety anywhere on this porch.
I was told the previous homeowners were elderly and likely didn't get too near to the screen. Still, it would be easy to lose one's balance or trip nearby and fall right through that screen!
The buyers have small children, so this porch will have to be made safe with proper guardrails and a receptacle.
There is an old ceiling fan (the edge of one paddle is visible) which rusted out long ago and is unusable. That might need some attention too!
My recommendation: serious attention should always be paid to unsafe living conditions. And in every way. What one homeowner might have been used to, even for decades, is still unsafe. Buyers need to pay attention to the safety of every aspect of a house, inside and out.