The guiding principle in the design of the SF90 XX Spider interior was to highlight the cockpit's racing vocation through targeted actions that would make significant weight savings. The main areas involved were the door panels, tunnel, and mats, which are now simpler in terms of their shape and the materials used thanks to an emphasis on technical fabrics, while carbon fiber was used for functional areas. In addition, carbon fiber racing seats were specially designed to enhance sporty driving pleasure, without compromising comfort.

The SF90 XX Spider allowed the Ferrari Styling Centre to use the modifications made to the rear of the car to create an instantly recognizable architecture in which the flying buttress seamlessly melds with the arrow theme of the front. The resulting visual effect creates a completely different connotation to the SF90 XX Stradale. The car's center of gravity appears lower, particularly from the side. This is not just because of the roof but also because the flying buttresses are lower than on the SF90 XX Stradale. The top is comprised of carbon fiber and can be opened while the car is moving in a mere 14 seconds, allowing occupants to enjoy the car to the utmost in all kinds of weather. Styling-wise, the SF90 XX Spider incorporates the engineering principles that underpinned the SF90 Stradale and pushes them to new levels so that there is no doubt that this is an XX car. One of the most distinctive characteristics of the SF90 XX Stradale's design is its rear wing giving it the long tail silhouette typical of racing cars with the advantage of improved aero and cooling. The SF90 XX Stradale's styling cues are designed to highlight its thoroughbred performance characteristics whilst still retaining the pure lines and forms of its predecessor.

The SF90 XX Spider has inherited the SF90 Stradale signature PHEV layout, in which the V8 internal combustion engine is integrated with three electric motors, two independent on the front axle and on located between the engine and gearbox at the rear. This configuration has been further refined for the SF90 XX Stradale by increasing the compression ratio and removing the secondary air system which allows the car to unleash a maximum of 1030 CV, (+30cv more than the SF 90 Stradale) setting a whole new Ferrari performance benchmark.