If I Downgraded my Storage plan I previously bought on a phone with smaller GB, will it take away some of my storage on my new phone?

I ran out of storage on my old iPhone SE so I was paying .99 cents a month for 50 GB, but now I have an iPhone 8 Plus which is 64 GB. ICloud was continuing to charge me .99 cents a month and I just now figured out how to discontinue it, but it said that if I did so I would only have 5 GB of storage. Should I be concerned?

It's saying that if you stop paying, your cloud storage goes from 50 GB to 5 GB since that's all they give you for free. It doesn't affect local storage on your phone at all, other than you might be using more of it since it can't store as much in the cloud.