Without having any amount of expertise in the subject, could it be that you have some muscles that are too weak to perform these movements at this point?
I had glute weakness and was helped by simpler bodyweight exercises to alleviate that, although these were prescribed by a physiotherapist so if that's an option for you that might be a good route to go.
What do you mean by can’t complete the sets? How is your workout structured?
Typically you would choose a number of sets, each with a number of reps. Say 3 sets of lunges at 8-12 reps. You choose a weight such that you can complete at least 8, and keep pushing each week until you can do all three sets at 12 reps. Then, add a little weight and start the process over.
If you can’t do bodyweight lunges, that’s okay! You want to progress other exercises until you can manage it, perhaps bodyweight squats, then goblet squats holding 10lbs, then eventually the bar and however much weight you can add to it.
For youtube in general I recommend Jeff Nippard. I don’t know of a resource that’s dedicated only to barbell but the barbell is pretty much the foundation of working out, most things can be setup for it
Well so far I've been doing for legs are the following
Squats 3 Sets 6 Reps
Barbell Lunges 3 Sets 6 Reps
Sumo Deadlifts 3 Sets 6 Reps
Side to Side Lunges 3 Sets 6 Reps/Side
I can complete the 3 sets of squats and the sumo dead lifts I have no issues there but struggle immensely with the lunges. I'll check Jeff but I think I'll need to work out into refining my workouts so I can get the most out of them.
So how many sets do you manage?
Honestly I cannot even complete a set like I could do 6 with my right leg but basically none with the left one, is like I'm blocked and my thighs shake like crazy
It's okay to leave them out of your program too. Squats and deadlifts already cover everything that lunges would. Focus on those movements for a while to strengthen your legs. Then when you're ready, you can either swap one of them out or just add lunges back in.
Then I'd suggest you reduce the weight until you find something you're comfortable with, and slowly build up from there. You don't need to use the same weight for every single exercise.
To build general strength in your thighs, it's best not to do repetitive motions as well but to hold certain positions longer and longer.
Look up the Warrior 1 yoga pose for example, it's basically a low lunge with your arms raised straight up. Do that as a warm-up (hold for 5, 8, 10 seconds increasingly) and build up your thigh muscles.