I think

I could take all of next week off from work. (I have enough vacation days left).

could be translated to “Je pourrais…”. And

I might take all of next week off from work.

could be translated to “Je pourrais peut être…”. But I don’t think a one word translation exists in French to differentiate “could” and “might”.

IMO, I could is like “I can, if I want it” but I might is “I can, and I kinda want it”.

As a french native, to translate I could take all of next week off from work. (I have enough vacation days left). I would say :

Je peux poser la semaine prochaine. (Il me reste assez de jours de congés)

This sentence indicates that I can, but that’s it.

But, to translate I might take all of next week off from work. I would use conditional :

Je pourrais poser la semaine prochaine.

This sentence indicates that I am hesitating or at least thinking about it.

For "might" with the sense of intention, as in you’re considering it, I think there are a lot of options:

Je pourrais peut-être poser la semaine prochaine.

Peut-être que j’aimerais poser la semaine prochaine.

Je considère poser la semaine prochaine.

Je crois peut-être poser la semaine prochaine.

Peut-être que je poserai la semaine prochaine.

Et si je pose la semaine prochaine.

For "could" as in you would be able to if you wanted, it’s a little more limited:

Je pourrais poser la semaine prochaine.

Je serais libre de poser la semaine semaine.

I’m sure there are more minor variations for both, and no doubt some overlap as there is in English.