Based on his two-page appearancein MTMTE, this is a repainted and mis-transformed FOC Optimus. I had to swap his hands around.
The head is a classics Prowl with antenna from a FOC Ultra Magnus. I had to slightly widen the bonnet cavity for it to fit.
I painted the detail on the soles of his feet
This is the artist's sketch I tried to follow.
Hopefully the photo site I use isn't playing silly games with me again.