all the profile meshes are made roughly to real life size. whereas in blender, the default size is usually larger, for example the monkey head is 2 meters tall.

the solution is scale up all source mesh.

1. go to addon folder, by default it is "C:\Users\UserName\AppData\Roaming\Blender Foundation\Blender\3.5\scripts\addons\Handy Curve Profile", locate the "Handy Curve Profile.blend" file.

2. open the blend file, optionally, import an object as scale reference. select all profile meshes - scale them accordingly - apply object scale- save blend file.

next time when you use the side panel to add curve profile, the scale will work to your liking.

1. create a folder at a place of your choice. for example a folder named "My Curves" in D drive.

2. go to the addon folder which usually at "C:\Users\UserName\AppData\Roaming\Blender Foundation\Blender\3.3\scripts\addons\Handy Curve Profile" UserName usually is your main admin name, 3.3 is blender version, it could be 3.2 or others.

3. copy the "Handy Curve Profile.blend" inside default addon folder to your custom folder "My Curves".

4. in your addon preference set the custom path, please NOTE: only point to the FOLDER, NOT the actual blend file. 

5. save preference and every time you make changes, such as append new mesh, it will work on the blend file in the custom folder. you may set up multiple folders for different projects.