I know this is an old thread, but it was at the top of my Google search so I thought I’d add some new information, which I found in the issues thread linked by Burt_Harris.
You can’t seem to change the formatting of values displayed in the Locals pane or in tooltips, but you can force the formatting on variables in the Watch pane by appending ,x to the variable name.
Other formats exist, such as ,b for binary, ,o for octal. I believe it’s based on the GDB display modifiers uses (e.g. display/x myVariable)
Suffixes used in VSCode’s Watch pane:
