It doesn’t look like it’s as easy as ticking checkbox anymore:
There is toolbars settings, while more customizable, it requires manual JSON editing:
Click Edit in settings.json, and replace “Upload” entry with:
{
"text": "$(arrow-right)",
"tooltip": "PlatformIO: Upload and Monitor",
"commands": "platformio-ide.uploadAndMonitor"
},
Found this solution in other topic as well: Shortcut to "Upload And Monitor" task while also restarting it if active? - #6 by soudgithub

