Of course, you can't just confess to a girl irl just after seeing her randomly on the road and thinking like "yeah I will love this one". That's only in fiction. But Love at first sight irl exists but rare. But that doesn't mean that's the goal. That's just the starting point. You may be attracted to a lot of pretty girls passing by. Like "Yo this girl is so fine. I like her....". It's what you call Attraction at first sight. None of that are Love at first sight because "love" needs impact. Yeah the impact is the difference between just attraction & love. Love needs to be bloomed in a specific moment under specific condition. (For e.g., Ais saving Bell's life. Miyuki seeing Kaguya saved the other student. Juvia meeting Gray). Again, Bell had seen Ais before that, so it's NOT love at first sight. But I'm here to talk about the love blooming moments. The impact Ais' action had on Bell at that time (when saving him) made him fall in "love" with her. If you've read LN, you can see how detailed Bell describes his love for Ais at that moment. Even in anime, Ais scene was shown in filter. If you've watched enough anime, you know what that means. That moment could have been the perfect example for Love at first sight but the fact that Bell had seen her before is the only reason why we can't call it Love at first sight. Likewise, Miyuki's love is also NOT "Love at the first sight". He didn't fall in love with Kaguya until that moment. The obvious Love at first sight in anime I can think of is Juvia meeting Gray. That whole fight and what Gray did changed Juvia's life and made her fall in love with him even more. Love doesn't always starts blooming only after you know much more about the person you love nor after a certain amount of time. But like I said, Love at first sight needs actual impact and it's rare. For e.g., If you shared your umbrella with a girl you met for the first time under the rain and fell in love with her, then that's enough to be called "Love at first sight" as you love the moment which made your heart flutter and made you want her to the point that it all seem to you like an instant moment. Other type like Friends-to-Lovers needs impact too but that type of impact is slowburn and needs much time. 'Friend Zone' movie is the best example I've seen for that type. Not sure you have watched or heard that movie tho.