This article offers steps of converting a VLESS link to a Sing-box configuration through a website.
Copy your VLESS link
Take Nekobox windows app for example. Open Nekobox. Click on the VLESS link you want to convert, then press Ctrl+Q. Copy the text starting with vless:// on the popup.
Open converting website
Open https://v2rayse.com/en/node-convert . Paste the text into Node Converter. Choose Sing-box in the dropdown list. Click on Convert button.
Save Sing-box Configuration
Click on Download button on the popup and you will download a JSON file to your computer, which is the file you can import to Sing-box app on your devices， such as Sing-box APP on iOS devices.