FIRST: this is not a "Forum Feedback" issue,
you really ought to post this in a more appropriate forum area.
But, as long as you are here...
You never mentioned what you wanted to use the panel for, all you said was "I've been thinking about getting a solar panel."
As long as you are just thinking about it, then why are you thinking about buying a 24V panel for a 6V application? Solar panels can be configured to have different voltage outputs. A solar panel is constructed of a series of individual cells, all having a relatively low voltage, like in the 1 to 2 volt range (depends upon the material used and the amount of light).
So, just find a panel that has an output voltage already in your desired range.
If you were to wire in dropping resistors then to arrive at 1/4 the output voltage (24V down to 6V) means you would be wasting 3/4 of the output.
There are voltage changing circuits that will convert one voltage DC to a high frequency AC then using transformers to step that up or down to some other voltage and then rectify it back to that other voltage DC, but all that still is going to cost something in the conversion process.
Just find the right panel to begin with.
If you already have a 24V panel, then see if you can get to the wiring between the cells. If so, then you might be able to just use 1/4 of the cells to have your desired 6V output. If you are hoping to charge a 6V battery then you may want to consider using a slightly higher number of cells (or a slightly higher output voltage, like about 8V) so that you can actually recharge the battery and not just maintain some output voltage.
There are many things to consider here, and I am not going into detail here, not that I don't want to, but, like I started, this is not the appropriate forum.