you might want to create a Design preset or theme in PowerPoint. This will help you apply the same design to all slides at once, and you can also send the theme to anyone for use by them.

A PowerPoint Template or Theme consists of slides or a group of slides with unique layouts, fonts, colors, design, effects, background options, and so on. Choosing the right theme or template for ...

You can edit a PowerPoint template by adjusting its theme settings ... you can apply a template afterwards. Head to the "Design" tab and select one at the top. 3. Once you've chosen a template ...