You can get to the Widget Inspector with Ctrl + Shift + W. However, when you change settings within there they won’t persist through a restart of the editor so you’ll have to do it every time. I created a really simple plugin to allow configuring the UI scale as well as disabling Slate tooltips (GitHub - nikkomiu/AdvancedUI: Unreal Engine 5 Advanced UI Editor). Feel free to open issues or create PRs to make it better 
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