VSCode-SFTP enables you to add, edit or delete files within a local directory and have it sync to a remote server directory using different transfer protocols ... Installation · Usage · Example configurations · Remote Explorer
sftp sync extension for VS Code. Syncs your local directory with a remote server directory. Allows you to optionally edit upload a file to the remote directory.
The documentation for this extension lists available commands, one of which is SFTP: Upload Active File (which can be issued from the VS Code command palette)