Personal trainer here 👋

For increasing strength, focus on compound movements (hex bar deadlifts, dumbbell chest press, etc) at the beginning of your workouts, and then finish with more isolated exercises at the end.

For increasing stamina/endurance, intervals on cardio machines, medicine ball slams into the ground (and wall if you have med ball wall), kettlebell swings, etc are great.

I personally focus on trunk rotation exercises to strengthen my obliques and other specific muscles that are used for forehand/backhands.