Javelin does not have a native way to do this, but you could use Javelin to run a PowerShell script which is SFTP capable.
The attached file, pwshellexample.vwf, is a Javelin PowerShell script execution. It does so by spinning up a Process object. The scriptFilename variable holds the PowerShell script location and logging the Console Output at the end. We don't have specifics on using PowerShell to perform SFTP or FTPS but it should be possible. This is an example and as such does not have error handling, but this should be easy enough to do if you look into the Process Object properties and methods and handle it in your code if needed.
You could also replace the scriptFilename variable contents with actual PowerShell commands such as Write-Host 'Hello'. Ideally we recommend keeping it pointing to an actual script file.
For more information on making PowerShell do FTPS and SFTP see the following link: https://evotec.xyz/easy-way-to-connect-to-ftps-and-sftp-using-powershell/