Wix doesn’t directly support APIs like Booking.com or other B2B travel platforms, so adding a flight search tool (like Expedia) to your website has some limits. Here are a few options:

1. **Custom Code with Wix Velo**: Wix has a tool called Velo where you can add code to your website. Some flight and hotel services let you use their API, so you could add a search feature this way. You might need a developer for this option.

2. **Use a Booking Widget**: Some travel services offer simple widgets or iframes (like a mini website) you can embed. If you get one from a travel provider, you can paste it into your Wix site to show a search or booking option.

3. **Whitelabel Solutions**: Some travel companies offer whitelabel products you can customize with your brand. They can sometimes be added to Wix as an iframe or link. You’ll want to check if Wix can support it before going ahead.

If you want a full booking system, think about a platform designed specifically for travel agencies too. It might work better than Wix for big features like flight booking.