can you change size (dpi) of photos i Photos or iOS

I often need to change the size of a photo for web use. I do this now in Photoshop. can this be done in Photos for iOS? Trying to avoid getting a subscription to Photoshop just for that. Just purchased new iMac and haven't seen it yet in person. But looks like in Photo for iOS I can adjust lighting and crop. I often save a large photo,300 dpi, but also need to share on web at smaller and at 72 dpi. Figuring can do that w Photo, right?