little sister?  
no, the guard is not small. I used a player.setscale command on my oc to make she a bit larger. normal size is player.setscale 1 I put player.setscale 1.1 and stayed like this. yes my oc is really big as well as celestia
 
if you are new user you will need to enable the use of mods in your fallout by going to the files ini in the folder where your saves is.  
look for a tutorial on this on the internet. search for something like: fallout 4 ini mod activation  
and download de nexus mod manage in nexusmod site
 
used mods in this image
 
1: Caliente’s Beautiful Bodies Enhancer CBBE https://www.nexusmods.com/fallout4/mods/15  
(for bodies new pretty mesh =.)
 
 
2:Bodyslide And Outfit Studio  
https://www.nexusmods.com/fallout4/mods/25  
(for adjusting my pretty bodies =.)
 
3:RaceCustomizer  
https://www.nexusmods.com/fallout4/mods/15212  
(other mods of race change etc need this plugin =.)
 
4:(CaN) Crime Against Nature  
https://www.nexusmods.com/fallout4/mods/19040/  
(this is de real pony race mod =.)
 
5:Fallout Equestria 4 - Fallout Equestria  
https://www.nexusmods.com/fallout4/mods/23109  
this changes all the characters of the game to ponies. OBS! may not work on the new CaN. you will need to find the missing file in the NMM plugin tab. I do not remember where I found the missing file =./
 
6:CaN Mane and Tail Addon  
https://www.nexusmods.com/fallout4/mods/21695/  
(more mane and tails options and better work =.)
 
now the rest is vanity of mine. clothes weapons etc. fortaleza armor