You can check the Respins which are the ISO’s updated here Index of /pub/alt/live-respins. But I imagine that Plasma 6.3 would only be included if is planed to be delivered to current versions of Fedora it will be include in the updated ISOs.
You can also download the much smaller netinstall image and install your system with the latest packages available. Best method for installing Fedora, way underrated.
Not when you install using netinstall, your system is up to date, right after install.
Unlike the netinstall images of other distros, Fedora calls this the “Everything ISO”. I guess the name has a point, you can install everything and it just downloads everything.
Unfortunately, the everything-netinstall image is a bit hidden on getfedora and not marketed at all. The only downside is that it can’t be used to boot live environment for testing.
In the end I used the Everything ISO, and indeed I got a system that was right up to date, with Plasma 6.3, and sudo dnf upgrade telling me it had nothing to do.