There are two officially supported file extensions that allow automatic installation of Behavior Packs and Resource Packs into Minecraft Bedrock Edition; ".mcpack" and ".mcaddon"
First is ".mcpack", which is what CurseForge currently allows
+Allows installation of a Resource or Behavior pack but not both
+Very useful for texture packs or very simple data packs
-Requires two downloads for most mods as Bedrock Modding requires both a Resource and Behavior pack in order to provide the full functionality
Second is ".mcaddon", which CurseForge currently does not allow when uploading files for Bedrock. This is a newer format specifically added to enable installation of addons.
+Allows installation of both a Resource and Behavior pack at the same time (see Attachment 2)
+Lowers total file size compared to having two distinct files
+Is the standard mod export type of ".Bridge", one of the most popular editing tools for mod creation.
+Prevents every mod from having to put "Remember to download and install both files!" text on the description (which is often ignored, see Attachment 1).
+Would prevent inflated download counts as currently every proper installation of a mod requiring both packs would count as 2 downloads.
Attachment 1: Image showing a download page of a mod that requires both pack types. BP downloads circled in blue, RP downloads circled in red. Showing that one has 34 downloads and the other has 18, meaning that at best there are 18 people who have both files, meaning that the remaining 16 cannot use the mod properly and will recieve errors when attempting to start a world with the files enabled.
Attachment 2: Image showing the contents of a .mcaddon file: Two folders, one labeled RP and the other labeled BP. Both of these will be installed upon opening the file.