iOS13 is out on friday along with the release of the new iPhone 11 and iPhone 11 Pro
First before installing iOS 13 – backup your phone – use iCloud or backup to iTunes on your computer – I prefer you to use iCloud
Here is a link to assist you in backing up : How to Backup Your iPhone
It’s a good idea when installing a major update to review the apps you have on your phone and remove the ones you don’t need
The last question is :will you be able to install it on your iPhone ?
The earliest iPhones where you can install iOS 13 is the iPhone SE & the iPhone 6s
Also check if you have enough room to install it.
iOS 13 is full of many new features and is a great upgrade to the operating system on the iPhone