insecure

If it makes you feel more confident and happy about what you see in the mirror, then yeah it’s going to help.

You’d probably get some detractors who won’t be able to help making remarks but all they’re really telling you is they’re not your friend.

You can also do something natural looking that most guys don’t recognize as ‘makeup’ but helps improve your look.

There’s more men who do this than you might realize, e.g. anyone behind a news desk on tv

It doesn't have to be makeup, but caring for how you look can help you feel fly, too. A haircut that fits. Face treatments or creams with nice scents feel good. Finding the right products for you can make you feel good. I helped my husband find the right soap and shampoo for his skin and hair type, got him to use moisturizer and better shaving products. His acne that he had for years vanished completely, his skin is nice and smooth now and he feels so much better because all the dry skin was uncomfortable. He also goes to a barber shop now that massages his head and gives him a haircut and beard trimming and he loves having a little spa time.

It won't magic magically cure your depression or reduce your weight, but it will help you feel better in your body.

No, because the thing that makes a person feel good when they wear makeup is the anticipated reaction of their peers. Per modern grooming standards, straight men (assuming you are straight here) are expected not to wear make up, and thus will garner quizzical or negative reactions from the average person. You already know this, and if you didn't, it would quickly become apparent once you started interacting with anyone. And once you noticed others' negative judgement, you would not "feel fly".

Instead the way to "feel fly" is simple, if not easy - hew better to culturally agreed-upon beauty standards. Cultures and subcultures differ in exactly what this entails. But common things are wearing clean clothes without obvious wear that fit well; getting a good haircut; taking care of your skin; eating a healthy diet, getting exercise, and sleeping well to improve mood and energy levels; unabashed self-expression within cultural constraints through clothing choice, haircut, hair color, tattoos or piercings, or accessories. And, most importantly, by not being overweight.