Yes. Example -
To do that, do a Get Info on the folder you want to change. Select (click once) the icon in the upper left of the Get Info window, then Copy it (Copy in Edit menu, or Command-C).
Then open Preview. When Preview is up, go to the File menu and select "New from Clipboard". This should open the folder icon in icon mode.
In the list on the left, be sure the #1 (topmost) item is selected.
Then go to the Tools menu and select "Adjust color...". Then use the sliders to adjust the color; the ones I usually use are Saturation, Color, Tint, and Sepia.
Once you're satisfied with the change, click once in the large representation of the icon, then Copy.
Go to your original folder, do a Get Info on it again, then select its icon in the upper left and Paste.
Note - you can save the work in Preview as an icon file. With Preview still active, select Save from the File menu and you'll be prompted for a name and deposit location.