A small courtyard lends itself well to a tropical planting scheme. It could look like this…
With small spaces, you need to go big with foliage and leaf shapes. Packing your space with lots of plants will make it seem larger and deeper. Palm trees, bananas, cannas, ferns, olive trees can all grow well in size appropriate pots. Then you can add smaller pots for seasonal interest - bulbs, pansies, aubrieta for the winter and spring, then annuals, pelargoniums etc for summer. Don’t forget scent - sweetpeas, stocks and nicotianas grow well in pots and will perfume your entire courtyard.
I would also recommend a pot irrigation system, it makes a huge difference. Remember also that pots need a lot of feeding as the compost gets depleted of nutrients quickly, so enrich your compost with manure/blood fish and bone/slow release fertiliser when you plant, and make it part of your routine to feed the pots ( with Miracle Gro, Tomorite, liquid seaweed etc depending on what you grow). I have a lot of pots and feed them weekly in summer, and they remain lush and productive until the frosts.
Not all perennial climbers are happy in pots, but consider annual ones like morning glory, it is extremely vigorous and floriferous and comes in lots of colours.