Sleep training?

Hi ladies, is there any method how to sleep train 2 year old?

My boy is good sleeper for nap and bedtime but he doesnt fall asleep on his own.

Normally we do bedtime routine about 30 mins, then one of us takes him to bed, lights off, just some white noise and then we have to sit next to him while he is trying to fall asleep in his bed..we usually spend in his room about 30-50 minutes everytime.Naps and bedtimes too.Sometimes I even have to hold his hand because he doesnt want me to leave.😵😵😵We also have 2 months old baby who needs attention all the time so I cant really afford to spend almost hour sitting next to my son quietly in dark until he sleeps😔😔

I wish if I could take him to bed, read him book and then kiss and say goodnight and leave.Then he can fall asleep slowly on his own.But when I tried this he was fine couple of minutes and then he was crying/whinging.

Any ideas how to teach him to fall asleep on his own please? I am quite desperate😑