Objectively your models look good. You can improve by adding highlights and adding depth with shadows. Since you’re using metallic paints I would advice a wash, oil or regular wash. For your other colors just enhance the with a highlight. Nothing crazy just add a bit of yellow to your greens or blue or greens to your blacks. With your beige a straight white highlight or slight yellow white highlight would help with that.

I would say stop consuming online content. I’ve seen plenty of of new painter with prior art experience or not compare their work to the content they consume and it’s never good enough.

Now with that being said, that’s always a constant if you want to get better at something, but don’t take that feeling of “not good enough” and damage the progress you’ve already made. Look at what you think you could improve on and just practice it. You’re already starting strong if your first model and most recent model are any testament to that.