Yes, you can sell multiple items in a listing, but once the listing has sold you will be obligated to transfer all items at the finalized listing price.
If you want to create a 'package' of various online properties - websites, domain names, apps - you can, but that package will need to have a single price.
You will have to select a "headline" domain/asset which will have its ownership verified. Other items can then be mentioned in the listing description. Once you have started your listing, you will not be able to edit the details - so ensure that you have confirmed that all assets within the description are what you would like to sell.
If you are selling assets which are generating traffic and/or revenue, then the appropriate proof of said traffic/revenue will have to be added to the attachments of your listing. If you have further questions on providing revenue details, you can read more here.
Lastly, keep in mind that you'll usually receive a lower price for a 'package' than you would if you sold each item individually.