Most of my photos come off my phone....LOL... I know... I know, but that is what I usually have with me. Fortunately some of my older family photos that I have been using for sepia were scanned in.

When I download them to the default photo program on my windows, it doesn't exactly have sepia, but it has a filter called sunscreen which gets it close, but sometimes a little dark. I can adjust that with the color slide.

Before I knew I could make that work, Old Guy suggested GIMP which is a free to download editor. It takes a couple of steps once you drag your photo there, but it's pretty easy and has lots of other fun things to play with.