I'm trying to change the settings and can't find them anywhere. On forge it says "Fabric 1.14+: Mod Menu > Config" but I can't find a mod menu button. Does this mean I need to install the Mod Menu mod to use the settings?

sadly you do, this is currently the annoying for fabric

edit: if you are on forge you should have access to it already

Installing that mod shows the settings but surely you don't need another mod just to access the settings?

Ah so it's assumed one has this installed and there's probably a pending PR on fabric to merge this?

No, on Fabric you just install Mod Menu, there is already support for that.