Attached are the other rooms

Even the new blue pieces are dark. I'd lighten up the heaviness of the sectional with a faded area rug in blues, and aquas.

I'd put the largest sofa section on the solid wall.

https://www.wayfair.com/Bungalow-Rose--Machine-Washable-Oriental-Ivory-Blue-Area-Rug-With-NonSlip-Backing-X233491514-L167-K~W122380403.html?channel=GooglePLA&ireid=476678013&fdid=1817&PiID%5B%5D=399481410&refid=GX711246481904-W122380403_399481410&device=c&ptid=2437571247995&network=g&targetid=pla-2437571247995&gad_source=1&gad_campaignid=660798157&gbraid=0AAAAAD9ISC4GBqVlxtHQ_u_NwvKzurLXm&gclid=EAIaIQobChMI_YWbv9L7lwMVYgZoAR3k-jMxEAQYDiABEgKI2_D_BwE

Thank you, I did like something like this I saw

No blue walls since we have the blue couches

you can do coastal inland by keeping it airy instead of themed. since the blue couches are the anchor, go sandy and white everywhere else: natural jute or sisal rug, white or driftwood-tone side tables, linen curtains hung high on those big windows. add texture with rattan or a woven basket, and skip the anchors and seashell decor. a few soft blue and sage pillows will tie the sofas in without adding any blue paint.

Here is a quick render of your space with the sofa and other coastal decor. I would suggest to use black trim in the pillows, a throw or ottoman to tie in the window frame. You absolutely can put coastal related artwork but you don't have to. Just use light greens, blues, seafoam green etc to lighten and carry the space to your desired style.

Using a lot of white can bring out the contrast of the black trim as well. I would normally say to keep the trim light to give that airy, breezy ocean feel but since you already painted them, just focus on bringing out the window color in your decor. Adding some light colored flowers in the  coffee table with seashell decor and other items can also give off that style.

You can absolutely do coastal without a beach outside! Think of it as a feeling: light, airy and natural, rather than anchors and signs. Your blue sofas are a great anchor, so build around them with sandy neutrals and white. A jute or faded blue-and-ivory rug will lighten the dark pieces, and white or natural linen drapes hung high and wide will brighten the whole room.

Then layer in texture: a rattan or woven light fixture, a light wood or whitewashed side table, woven baskets and a few big green plants. For art, choose one or two larger abstract seascapes or soft watercolor pieces instead of lots of small beachy accents. Repeat a little of the same blue in pillows and the dining room so the spaces feel connected.