Apple will only let you buy the most current version of logic which requires at least Ventura 13.5. There is a work-around. You would need to find someone that is using a mac with at least that version of MAC OS or newer. You open the APP STORE on their computer and log in with your Apple ID. You can then buy the current version of Logic. Complete the purchase but don't download. Log out of the APP STORE application.
Now go to your computer and log into the APP STORE with your Apple ID. Click your profile on the bottom left of the window. The next screen should show your purchases and look for Logic Pro. Do not click on Logic Pro itself. Click on the download symbol. It will bring up some message asking if you want to download the last compatible version. Click download and you should be good to go.