The scanning telescope had a 60 degree field of view and 1X magnification, so planets within that field of view would have been visible.
The scanning telescope could be moved +/- 270 degrees in one axis and -5 to +50 degrees in its other axis. It was normally moved simultaneously with the moveable line of sight of the sextant. The large degree of freedom is around an axis normal to the surface of the command module, the other is perpendicular to that. The manuals call the axes "shaft" and "trunnion"; I would call them "pan" and "tilt".
Larger movements would require maneuvering the vehicle.
Note, however this comment by Collins about the telescope.
As a general comment, I've found that the telescope was a very poor
optical instrument in that it required long, long periods of dark
adaptation before any star patterns were visible.
And similar comments by Armstrong
I think we already covered that by saying that with the LM on in the
daylight the telescope is nearly useless and you have to rely on the
sextant. Now, we never went into that mode that Apollo 10 discovered
of pointing the plus X axis at the sun. We never had an occasion or
need to do that. Therefore, we can't comment on it. Just staying
regular PTC attitude, normal to the sunline, the telescope was just