How big is the deck? Do you need a bbq?

Also where is the door?

The deck is 12’ x 20’. The door is on the same side of the house as the stairs.

Our deck is 10x24 so not that different and we have a bbq, table for eight, and sectional with coffee table.

Do you happen to have a picture?

If you place couch facing the lawn and two chairs facing in, if table is not too large, and the BBQ is located where blue chair is…it might work. You may want to measure: note the length of the couch you would be buying and then you’ll get a sense of what size table is possible.

I'd get two couches and two swivel chairs. OR a sectional, you may want to take a nap on the deck.

https://www.homedepot.com/p/Brown-5-Piece-Wood-Outdoor-Wicker-Patio-Conversation-Sectional-Seating-Set-with-Beige-Cushions-THD5-CR01902S/339739039?source=shoppingads&locale=en-US&fp=ggl&srsltid=AfmBOoqSWV6XPb2hXggiMTH_nDzQh0Lz9Q-bZ6ihMsoJxsl3_Fd-bI7KaEI#overlay

Here are some other angles

Most importantly, select a table and chairs that will be big enough to seat you family (& guest?). It should be centered on the deck in front of the sliding door. once that is place, measure how much room you have for other seating. I'm not sure you have room for a couch. Consider individual chairs and a few side tables which can be moved around the deck as needed. I find outdoor couches aren't as useful as you'd hope. People don't usually like to be seated too close to others when it's warm out.

I agree with Barbara a dining table plus deck chairs but add some lightweight ottomans or footstools to move around with the deck chairs.

We have plastic deck chairs that are adjustable to recline somewhat. Cushy seat pads are comfy enough and can be brought in from the elements.

A 12'X20' deck doesn't give you much space if you put it in scale. You can have a seating arrangement with a coffee table and a BBQ, or a table with chairs and a BBQ (maybe add bench seating to that), unless you want to cram everything on it and jump around furniture to get from one place to another.

Good luck