Do Palettes such as the basic math palettes exist on the online version?
No.
There are a couple of challenges to making this. Rich formatting of math on the web is kinda difficult even when the formatting isn’t interactive like it has to be in Mathematica for you to enter it via the pallettes.
There is a dialog for inserting special symbols. It’s available under “Insert” > “Special Characters”.
Ok but how about something simpler.
How do you generate a superscript in a Mathematica Online notebook?
Subscript still works:
Subscript[a,b]
Thanks. It was not what I wanted to hear but as someone said “Life is hard and then you die”.