I recently added Blubbos Shrub Replacer (BSR) to my list and, though I really like the new shrub models, they were simply way oversized when compared to the rest of my flora. So I decided to use Base Object Swapper to resize the shrubs, and since I was already collecting the correct asset names to add to the swap file, I figured I might as well add all the shrub meshes I could find while I was in the Creation Kit. 38 plants in total are included in the swap files.

This has lead me to create three versions of the swap file:

1) Shrubs Resized: This file is intended to be used as a DIY template. All the assets are included, with the scales set to "1". You can comment out the plants you do not wish to resize and input your desired scale for those you do want to adjust.

2) Smaller Blubbos Shrub Replacer: This file is already set up for use with BSR. All of the meshes from BSR are reduced to 50% of their original size, but all other plants are commented out and thus not adjusted by this file.

3) Smaller Blubbos Shrub Replacer for Happy Little Shrubs: This is the file I use myself. It is the same as file 2), except that the pine shrubs are commented out, and remain unchanged, as I make use of Happy Little Shrubs (HLS) along with Happy Little Trees and did not want the HLS meshes resized.

Note that file 2 and 3 are not dependent on BSR and BSR is not a hard requirement. The files simply adjust only the flora models replaced by BSR and no other. If you do not have BSR installed the file will still resize these meshes regardless of whether they are vanilla  or some other replacer meshes. These files were intended for use with BSR but are not reliant on BSR being part of your mod list.  

All screenshots were taken with Blubbos Shrub Replacer and swap file 3) Smaller Blubbos Shrub Replacer for HLS _ BOS.

Editing the swap file:
To make your own adjustments to the swap file open it with a text editor such as Notepad.

To "comment out a line" prevents that mesh from being adjusted by BOS. To do this simply add a ";" in front of the line. In the below example "TreeFallForestShrub01" will be scaled to 50% of its original size while "TreeFallForestShrub02" is commented out and will thus not be scaled and remain at it's original size:

;Fall Forest Shrub
;
TreeFallForestShrub01|scale(0.5)
;
;TreeFallForestShrub02|scale(0.5)
;

To adjust the scale of the meshes change the number in brackets at the end of the line to the desired scale. 1 = 100%, 0.5 = 50%, 1.5 = 150%. In the below example "TreeFallForestShrub01" will be scaled to 75% of its original size while "TreeFallForestShrub02" will be scaled to 125% of its original size:

;Fall Forest Shrub
;
TreeFallForestShrub01|scale(0.75)
;
TreeFallForestShrub02|scale(1.25)
;   

Installation:
Use your preferred mod manager to install as per normal.

Requirements:
Base Object Swapper and its requirements for SE and AE
Base Object Swapper VR and its requirements for VR

Credits:
Base Object Swapper by powerofthree
Base Object Swapper VR by alandtse