This body is achieved just through the vanilla character creation process; when on the body type triangle, simply drag the dot to the furthest bit of the "Muscular" corner. For more definition, you can use Muscular Female Mod by Tigersan.
Sorry, but this is the maximum muscles that the default NPC creation process allows. If you want more muscles, you'll need something that fundamentally changes NPC creation.
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https://www.nexusmods.com/fallout4/mods/29322
Every single person who has ever played this game has thought that.