Module style file is located at app/code/Magediary/AccessoryUpsell/view/frontend/web/css/source/_module.less If you want to change the style, then override the _module.less file here: ...
The countdown format can be updated from the backend configuration. Stores ⟶ Configuration ⟶ Magediary ⟶ Product Scheduler ⟶ Countdown Format {countdown} Moreover, we can update the launch and ends in time text format from the follconfigurations ...