Putting Pogba as a 10 would restrain him too much. He is better as a free roaming 8. He likes to start from deep but also provide width. At Juve, he loved to go on the left behind the LW who was cutting inside. Something like this.
And it would be more of a 4-3-3 than a 4-2-3-1/4-2-1-3 in this case. A bit more defensive but when you have someone as talented as Pogba, you can allow having Mctominay and Fred in a more defensive role.
Some people are confused about the difference between a #10 and a free roaming #8. The difference lies in where the player is on the pitch. Pogba won’t be able to do this kind of passes if he is too close from the edge of the box.
Pogba won’t be able to make the runs he likes so much as a #10. Here, he is starting from deep to then go between the lines to receive. If he was already positioned as a #10, it would be easier for the opponent to read what Pogba will do. It’s crucial to not be predictable.
You can argue that Pogba’s best game under Solsjkaer was when he was playing as a 10 against Bournemouth but when you look at his average position, he was operating as a LCM who was starting from deep and making runs into the box.