Sorry, I know this is probably a pretty common question, but I haven’t found the solution yet.
Basically, I’d like to know how to “unlock” the hands and feet in a rig.
The few models I’ve tried seem to have been rigged with Rigify, but I haven’t found the settings mentioned in a few places, such as “Rig Main Properties”.
Generally, rigify rigs and most others, have 2 modes. FK - forward kinematics and IK - inverse kinematics. FK means you have to pose every bone in the arm. Pose the Upper Arm, Lower Arm, and Hand bones. IK means you have a Hand bone and an Elbow Target bone. Pose the hand bone where you want, and adjust the elbow target as needed. Switches to control which mode you are in should be in the ‘Rig Main Properties’ panel, called an FK/IK Switch.
FK bones are in one bone collection/layer, IK bones in another bone collection/layer, and you can control collection/layer visibility under a menu around the ‘Rig Main Properties’ panel. I don’t use rigify - so I can’t tell you exactly where all the menus are…
Point is, if you’re in FK mode, you need the FK bone collection visible, and you should be able to pose those bones. Same for the IK.
If this doesn’t help, post up some screenshots and describe your problem a bit more…