If the oldest galaxy ever discovered, i.e GLASS-z13, is at a present proper distance of around 33 billion ly from Earth, why then do we define the observable universe to have a radius of around 46 billion ly? Is there anything currently 46 billion ly away from Earth that we can see?
The CMBR came from a sphere of matter with an extrapolated comoving radius of around 46 billion ly. That's the most distant thing we can see. The observable universe is sometimes defined to end there, because it's the limit of light-based astronomy, or is sometimes defined to extend back to the end of inflation, but the difference in comoving radius between the two is only one or two percent.
The distance to the most distant galaxy seen by a telescope should not be expected to converge to 46 Gly, because between the CMBR and the earliest stars there is a gap, called the Dark Ages, in which there should be nothing visible to telescopes.
We don't see stars and galaxies at a proper distance of 46 Gly, because this distance corresponds to a light travel time of 13.7 billion years, or very shortly after the big bang.
When we look into the distance we also look back in time. There was a time when there were no stars. The first stars formed about 100 million years after the big bang, which corresponds to a proper distance of about 38 Gly. Beyond that we can observe the cosmic microwave background, which was emitted shortly (400,000 years) after the big bang at a proper distance of 45.5 Gly. We cannot observe before that using light (or infrared, UV, radio waves etc) because the universe was opaque to light at that time, but we could, in theory, observe events prior to this if they emitted gravitational radiation or neutrinos (as the universe would have been transparent to gravitational radiation.
So the "observable universe" is defined as going right back to the big bang at a distance of 46.4 Gly. That is the volume of space that we could, in theory, observe. Even if in practice we can't actually see anything there.
Note that the distances that I quote are the outputs of modelling the expansion of the universe, and different assumptions about how fast the universe has expanded will give different values. That is, they are theoretical distances, not directly observed distances.