Design Templates | Where are they and how do you typically apply them?

Hey folks,

I have a meeting with my boss next week, and it's going to be revolved around asthetically pleasing Power BI backgrounds/templates. I want to be able to present him a bunch of different options, but I don't know where to go to get these.

For the past few months, I've been creating average backgrounds in PowerPoint, then bringing them into PBI desktop. Is there any templates like that around for myself to choose from, then edit?

Or are there just PBIX files out there with no data, but the theme/desgin is already in there? If anyone can provide me some sort of repository, I'd really appreciate it.

Thank you!