I paid for additional storage up till now I haven’t see it on my computer

If you bought additional storage, you bought iCloud Storage. You did not, nor could you buy additional storage on your iPhone. There is NO WAY to add memory to an iPhone. All buying additional iCloud Storage does for you is permit you to store more data in the cloud. It cannot and will not add space to your phone.

Read this link --> What's the difference between device storage and iCloud storage? - Apple Support

If you are out of space on your iPhone, you have delete things you don't need or use, such as photos, music, apps, messages, files, email, etc.

And if you are out of space on your iPhone, the next time you buy a new iPhone, make sure you buy one with at least, if not more storage than you need. Once purchased the storage on any iOS device is fixed at purchase.