After updating to the latest beta i have a question mark instead on iTunes. I can’t then do iOS 13 for my iPhone.
Lost iTunes after beta update
Yes, iTunes was removed in MacOS 10.15. Did you read the news and changes in 10.15 before you installed it? There are now separate apps for Podcasts, TV etc, and your iPhone management is now done from the Finder.
To install iOS 13 on an iPhoine or iPadOS 13 on an iPad, open a Finder window while the device is connected. You will find it in the sidebar and clicking on it will bring up a similar screen like there used to be in iTunes. Now option-click the Update button to select the ipsw file ...