Was it the boatneck look that you wanted to recreate?
Otherwise, if you just want a plain raglan jumper, there are lots of adult patterns available, including free ones.
I’m afraid I don’t have the time to watch the video, but if you can tell us how this one is knitted, we can help you find one similar.
For example, is it knitted top down? Seamed (made in pieces) or in the round?
Edit: Never mind, I found a link with that information:
https://sowoolly.net/how-to-knit-a-sweater-for-children-aged-2-4-years-step-by-step/
It’s knitted bottom up, in pieces.
There aren’t many patterns written for seamed raglans these days because they are well suited to knitting in the round, but I did find this free one from Lion Brand. It has a lace detail on the raglan lines, but that is easily changed. (Just do the raglan decreases like you did on the YouTube pattern instead.)
And add ribbing at the neckline.
Hope that helps!