ᐅ Replacing an old water tap valve

Hello everyone, in the photo you can see an old water tap inside a toilet cistern. It can no longer be turned. Do I need to unscrew the valve at the marked spot using a pipe wrench and replace it with a new one? Thanks, Ashley

Honestly: just a new flush tank, done. Everything else is a botch, judging by the condition shown in the pictures. That’s been installed for a few decades, hasn’t it!?