Hi @Febis1, let me see if I can help out here.
the easiest way to transfer data from your old phone to your Xperia 1 is to use the backup service made by Google. This way you will be able to transfer mail, calendar, contacts, applications, setting, call history as well as images, videos, music and other document files.
As both phones run Android, I believe that the Samsung S9 should have the possibility of backing up content to google, but for more information on how to do it, I would suggest that you contact the Samsung support. After the data of the Samsung is backed up, you can begin to set up your Xperia 10 Plus. When prompted in the setup guide to Copy apps & data, tap NEXT followed by either A backup from an Android phone or A backup from the cloud. Both options allow you to restore data from Google Drive.
Keep in mind that if you have already set up your Xperia 10 Plus, you will need to reset your phone in order to get access to the setup guide.
I hope that helped! Let me know if you have any further questions! 
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