Well - You can Download the Samsung Firmware from the link below & the link to Odin download is also available from sammobile.com on the same page
https://www.sammobile.com/firmwares/galaxy-s8/SM-G950W/I was hoping to see the Service Provider info in the About Phone screen shot...
You could also see if you can get the One UI update (Android 9) by using Smart Switch on your computer - You have to connect your phone to the computer and open Smart Switch on the computer - There's a "Download Firmware" tab near the top of the Smart Switch window - You can click on it & see if it will find the update for you...