You can make use of the Magento 2 Dropship extension, wherein after clicking the importer icon will bring up this pop-up. Here, the admin will be able to make use of the Magento end attributes if already created or can make use of the new attributes at AliExpress end to Create a Swatch for which the admin needs to check the checkbox option. If the checkbox is selected then the attributes will be created under the name Capacity at the Magento end.
Please do contact us for any further queries or requirements. You can also check our magento2 Extensions for additional features.