AN515-58 Is there any way to get the factory Windows OS image for my laptop?

If you have Acer Care Center installed, you can access the recovery option that will reload OEM windows and Acer apps. WindowsRE includes the version that was originally installed on your laptop's boot drive. Not sure what you are looking for, if you want to Clean install Windows11 here is the tutorial but that will not install the Acer apps: https://www.elevenforum.com/t/clean-install-windows-11.99/

You can back up your entire boot drive, including the OEM folders and recovery volumes, in Windows10-11 with Windows7 backup Image file creator (Control Panel) that will make a VHD (Virtual Hard Disk) image of your drive that you can mount in File Explorer on any Windows PC to browse or copy files. The VHD file can then be restored with the Windows USB Recovery Disk and you will have an exact copy of your original drive with all OEM files and Windows. You can upload the VHD file to Cloud, but it will take a while or store it on your backup drive. I do this monthly with a 4TB backup drive (40 minutes for a backup).

There is no way, you have to bring the laptop to Acer Services in your country to reset the system to factory defaults for a small service fee (in the Philippines $25), then you will have Acer Care Center to restore or you can make an image from your drive as I described above.

I live remote in the the mountains, North Philippines, and had DHL ship my Acer Aspire5 a515-54G to Acer Manila (1,000 km) for the same service (factory reset). Was charged nothing and received the laptop back at my doorstep in 2 weeks. Shipping was expensive though and had to crate it with a MSDS safety data sheet (to be downloaded from Acer Support site).