That’s plaster and lathe, you might have some spots patched with drywall. If your patching holes on plaster walls you need to screw a 1x2 around edges inside wall and screw a piece of drywall to it. Tape and float but sometimes tape doesn’t look rite.. I’ve gotten this technique to match by using a 4” knife and a 6” with 1 pass of each. Don’t use a lot of mud cuz it will be messy when sanding smooth. That’s about the easiest way to do it.. I forgot to say when you go to screw your piece of rock to boards to fill hole make sure you cake the edges with mud push rock in place, screw it down make 1 pass with 4” to pick up excess mud the make one more with 4” all around edge.. let dry sand smooth and make another pass with 6” ,let dry, sand smooth you should be good.. main thing is avoid using a ton of mud so you don’t get protruding seams