Improve

I am in the final round for an interview with a big tech company and it will be an onsite case study. I have never done one before in an interview and I am not the best when it comes to public speaking or presenting generally in person. I am looking for a crash course/guide on improving my speaking skills or anything that relates to presenting well in a case study. While there are tons of videos on youtube but wanting to know if anyone has been through a similar experience and found something helpful? Super nervous so any help will be appreciated. Thanks!