I think Russell would be a starter in today's NBA but it's unclear that he would be a center. If so, he would be the shortest starting center and one of the lightest. Sure, many decades later, if he were coming up now, he would have spent more time in the weight room, etc and be a bigger man. Wilt was already that guy, so his adaptation may have been a three, but I am doubtful of that given his issues/mental block at the free throw line.
Of course, if the greats had played against one another, perhaps they would have fewer faults. Young Shaq may not have ever become fat Shaq if he had Wilt or even Embiid outplaying him every minute and pushing him to be greater. Wilt might also have been shooting threes at today's version of Overbook High and making free throws from a young age when it was a known thing that such a weakness would be crucial when he made the NBA. As a kid in 1955, nobody was making that sort of planning for him. If he were a kid in 2015, his development would have been different.
Touch is its own thing and Embiid stands out among all time strong big men for that, although Moses Malone was similar, strong inside and nice touch at the free throw line. Russell was also relatively weak at the free throw line, just not awful as Chamberlain was. Russell was not a great shooter per se part of why he developed his role as a defender, which he was in the 1950s-1960s NBA, even though not at all a competent defender of Wilt.