TBH, I’m not actually sure what the unit for the "2" in <font size=2> is. XD I just noticed that when it's set to "3", it looks like the normal text size.

<font size=2>
The code block style in my local vault is created using the Code Styler plugin.
</font>

The result:

The code block style in my local vault is created using the Code Styler plugin.

References

1. Renanbr27. (2022, August 27). How can I change font sizes in Obsidian? [Reddit Post]. R/ObsidianMD. www.reddit.com/r/ObsidianMD/comments/wz2j4u/how_can_i_change_font_sizes_in_obsidian/