Echoing justanotherdev’s comment:
Mind-blowing and useful:
- Command Palette:
CTRL+SHIFT+p(Mac:CMD+SHIFT+p) - type
>transformpick upper/lower case and press enter

Echoing justanotherdev’s comment:
Mind-blowing and useful:
CTRL + SHIFT + p (Mac: CMD + SHIFT + p)>transform pick upper/lower case and press enter