Everyone is beautiful in their own unique way. Remember that looks are temporary and that there are far more important things than appearance. Whilst some may seem to surpass you in appearance, they may not do so in other respects (intelligence, kindness etc.). No one is perfect; so don't get too hung up one aspect of them like their appearance..
I recommend taking up self love meditations on YouTube and learning to love yourself and letting go of comparing yourself to others.
Jealousy is not always a bad thing; it can show you what you desire. What do you admire about these people? Is it their style or certain things about their appearance. Can you take inspiration from that an embody those characteristics; whilst embracing your unique characteristics. Is there anything you can do to change your appearance? .
I used to be bullied for my appearance a lot when I was younger; when I was older I had a major glow up and started attracting major admirers; to the point that I have been stopped in public to be told how beautiful I was. It is always possible to glow up, whilst simply enhancing and embracing your unique features. I only changed for myself and to step into my best most confident self.
I recommend experimenting with your style, going shopping and setting goals on how you can enhance you beauty. You can spend on makeup, skincare, jewellery, clothes, haircare etc. You may also start working out and eating healthily if it is your body you are insecure of; though such also has immense mental impact and can also boost your esteem.