Thats a decent routine although I would not recommend doing shoulders on leg day, Legs a large muscle group and should be worked alone, you also do not have anything there for your hams,
I would also suggest more sets in the leg routine
For example
Squats 4 x 8 to 12
Leg extensions 3 x 12
Lunges 2 x 30
Lying leg curls 4 x 8 to 12
Romanian deadlift 3 x 6 to 10
The reps I have stated are quite high, for building muscle I would prefer to do 4 to 6 reps to failure(this would be for the whole routine not just legs)
Personally I would recommend something like this, although it is a 5 days splt:
https://www.hypermuscles.com/f69/pow...ng-split-4772/ or this:
https://www.hypermuscles.com/f69/ret...training-6209/