Would you feel sexy if Leonardo DaVinci Painted Your Portrait?

I don't think women think you are thinking of them as "art" when you stare at their bodies. They are not psychic and will not be aware that your stare is one that should be equated with the kind of stare that you would give "beautiful art" without prior knowledge that you think in that way about women's bodies. As such, they are left to interpret your staring at their bodies in any way they wish and for whatever reason they might be inclined to interpret it in a way that you did not intend it to be interpreted.

I'd probably feel flattered.

Da Vinci was one of the greatest painters ever, as well as being a polymath. The normal rules never applied to him. He didn't just paint portraits, he did a lot of drawing, and he was famous for what he called his grotesqueries, which we would call caricatures today. He did a lot of anatomical drawings, and I'd be even more flattered if he'd chosen me as a subject for one of those.

As for feeling sexy...no. I've posed for portraits and as an artist's model before. It's not a sexy experience. Besides which, there is some evidence that Da Vinci was gay, though celibate for most of his adult life. Not conclusive evidence, but he was accused of sodomy. Even though Da Vinci was quite a good looking fellow of great personal charm, I don't feel sexy when a gay guy is paying attention to me.

there are many ways of respectful looking

Art doesn't look back - in the sense that art does not have its own living agency/consciousness

next time you look - hold a mirror up to your face and ask yourself what you see in your own gaze

people often forget, that looking at static images is very different to engaging with another human being - you do not have to respect a static image or film - you can engage with it privately and carry on any fantasy you desire

da vinci was one of the most brilliant people on the planet his portraits are beautiful....

EDIT: apart from agency - one can also leer at art or appreciate it - same with the body

No. His drawings aren't sexy for starters. They are old and faded but cool.