I would start by cleaning all the concrete. Then paint the walls including the storm door the color of the siding. Why not remove those stairs?

Is that a pleasant place to be with all the stuff that must filter down from the deck?

I would clear out the area and power wash the stairway and patio floor. Then paint the foundation walls a similar or lighter shade of the siding. Look at cement stains to use on the stairway and patio floor, something neutral to clean up the appearance. Then reassess the patio sitting area for how you want to use this space. Like hang some cute outdoor lights around the perimeter for a fun gathering spot in the evening.

We need the context of the adjoining area; beautiful backyard? Driveway/road?

Thanks all! love the feedback. cant remove the stairs as im only renting context: no backyard, but to the left leads down to waterfront I agree with the comment of things coming down from top deck (besides rain which would be inevitable) but thats no different than a fully exposed patio (imho). Def will be hanging lights around the perimeter, love that.

More please! :-) And thanks for the inspo!

Please clarify: Does the landlord want you to paint over the mural? Or do they have a professional painter who will do the work?

Do you use the space for anything other than storing chairs? If it were me, I'd use the deck and never use this space, so I wouldn't much care how it looks. Just because some former owner/landlord made a seating area here, doesn't mean you need to decorate it as one.

If you're only renting the lower level and this is your only patio, I'd paint the white door to match the mural (black, maybe), get an outdoor rug to match the mural and put some potted plants where they'll get some light. I'd string some lights under the deck. String lights always give a festive atmosphere.

I suspect the landlord would frown on painting the door, which looks to have the factory baked on finish on it. I know I would, if I were the landlord. You could put fake plants on the stairs, so they have a purpose. I am sure they probably went to that stairway landing at one time, and then that was closed in.

Show @lisedv's inspiration pictures to your landlord. That's the way to go if you're planning to use the space.

Regarding plants on the stairs, Begonia semperflorens, Impatiens, hostas and ferns could probably all cope with that amount of dappled shade. If you're still there in spring pots of bulbs could work since the trees will be mostly leafless. Keep to one or two types of pot rather than a mish mash and have them as large as will fit the steps to make them impactful and less prone to drying out.

^^^ I second that you can definitely do shade loving plants in containers. Just be prepared to water.

Lisedy has given you some great advice and a great starting point for your renovation. Just cleaning the concrete deck would make a big difference.

I was going to make the same comment re: shade loving plants. There are plants that would work on those steps.

ping pong table?

I love what Lisedv showed you. I'd add globe string lights underneath the decking and some faux plants and lanterns on the steps.

Even though some of the suggestions below would make the space look prettier, I just wouldn't hang out underneath this deck. Yes, there is shade, but I'm too claustrophobic. I'd paint it as others have suggested and get a nice chair or cafe table and chairs and sit them as close as possible to the edge where the sun line meets the shade. I'd just keep the rest of the space clean and empty.

No need for faux plants, which look tacky and would get dirty. There are plenty of real plants which would work there.

Thanks all! especially @lisedv for the pics!!!

Update! I found a drain in the sidewalk at the edge of the patio. What about making this a wet to dry transitional space. Run a homemade outdoor shower to rinse off sand, hang hooks by the useless cement stairs for wet suits and used beach towels?