Hi, GMC! Here is the tenth Study in D major from Matteo Carcassif's "25 Melodious Studies for Guitar".
It is a slur-mania with the pinky and the ring finger!
A series of triplets with hammer-on and pull-off will be a great tool for training to control your left hand fingers.
You don't need to "strengthen" them. All you need is "control". The preliminary exercise is the most important one in this lesson. You can even use it for your routine warm up exercise.
OK, Let's get started!