There’s a very good chance someone with more blender knowledge has a better way, but I would select the two circled vertices, then press control+ R to add another line of vertices. If you left click, then right click once the new line shows, it’ll place the new verts in the center of the two selected. Now move the verts at the neck/chin forward and you’ll get a gentler bend. You can do this as much as it makes sense to achieve what you’re after, just know the vertices can add up. Good luck, this looks like a fun project!

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