Hello! Baby is 6 months old, sitting on his side, has not yet started …

Hello! Baby is 6 months old, sitting on his side, has not yet started crawling on his belly, only sat down a couple of times, seemingly by accident. When he lies on his back, if you hold him by his wrists, he holds tight and stretches, then sits down. If he sits like that and you continue holding him, he stretches further and stands up. Is it possible to do this? He gets up and stands straight, laughing, I'm holding him, of course, not putting all the weight on him, but still...