Need help in powerpoint

Hey guys, just started my first internship at a small advisory firm, and I realised my powerpoint skills are pretty damn bad.

I read that one way to get better at slides is looking at the firm's previous slides to learn, but the firm I'm at has little to no slides to learn from. Those that exist seems to be of lower quality than what I have seen from sample pitches my seniors sent me.

Essentially, how can I improve myself such that I'll be ready for next internships in bigger firms that I believe would care more about powerpoints? Are there courses I can do?

Thanks all!