iPad 10 cover --> iPad Air?

The iPad10 is unique in its physical dimensions. Fitted cases, designed for other models of iPad, are unsuitable for use with an iPad10. Similarly, a case designed for iPad10 won’t fit other models of iPad.

There are many cases that are explicitly designed for the iPad - only a few being marketed by Apple:

Cases & Protection - iPad Accessories - Apple

Of manufacturers to consider, while there are others, perhaps consider STM, Otterbox and Zagg.

Hello RXT1885,

Welcome to Apple Support Communities. We'd be happy to provide some guidance. By comparing the size of iPad (10th generation), and the new iPad Air, we can see that they are slightly different.

iPad (10th generation):

Size and Weight:

Wi-Fi models

Height: 9.79 inches (248.6 mm)

Width: 7.07 inches (179.5 mm)

Depth: 0.28 inch (7 mm)

Weight: 1.05 pounds (477 grams)

Wi-Fi + Cellular models

Height: 9.79 inches (248.6 mm)

Width: 7.07 inches (179.5 mm)

Depth: 0.28 inch (7 mm)

Weight: 1.06 pounds (481 grams)

iPad (10th generation) - Technical Specifications

iPad Air:

Size and Weight:

Wi-Fi models

Height: 9.74 inches (247.6 mm)

Width: 7.02 inches (178.5 mm)

Depth: 0.24 inch (6.1 mm)

Weight: 1.02 pounds (461 grams)

Wi-Fi + Cellular models

Height: 9.74 inches (247.6 mm)

Width: 7.02 inches (178.5 mm)

Depth: 0.24 inch (6.1 mm)

Weight: 1.02 pounds (462 grams)

iPad Air

With that being said the case you got may not work for your iPad Air.

We hope this information is useful. Kind regards.