The C7(13,b9) or better and shorter C13(b9) is a dominant 7th chord with an additional minor 2nd (b9) and major 6th (13). While the 13 belongs to the natural tensions of a dominant 7th chord, the b9 is an altered tension. Both chord extensions have been described in the chord descriptions for 7(b9) and 7(13).
A C7(13,b9) has the notes C (1), E (3), Bb (7), Db (b9) und A (13). There's for sure no more space (physically and acoustically) for a 5th G here. On the guitar you'll normally abandon the 5th for the 13, that is located 2 frets higher.
The C13(b9) can be a great option, where it resolves from V to a I major chord, like Fmaj7 or F6, because in this case you can use natural tensions (9, 13) as well as altered tension (b9,#9 or b13) and therefore also a mixture of both.