tl;dr - No.

In Bedrock, unlike Java Edition, skins are a little messy; there's several types of skins available;

Regular Skins

If you used an imported skin, you can find them in [Data Root]minecraftpecustom.png of your internal storage. On:

• Windows 10, this is: %localappdata%PackagesMicrosoft.MinecraftUWP_8wekyb3d8bbweLocalStategamescom.mojang
• Android, this is: /data/data/com.mojang.minecraftpe/files/
• iOS (you can access a sandboxed version of this via iTunes Sync), but the actual file location is: /var/mobile/Containers/Shared/AppGroup/com.mojang.minecraftpe or /Apps/com.mojang.minecraftpe/Documents/games/com.mojang/ (depending on whether you are using sanboxed or rooted/jailbroken).

Store Skins

These skins are not stored on your device, and are unusable offline as they are stored differently to typical DLC.

Furthermore, some skins introduce custom models and higher texture resolution which cannot be transferred over to Minecraft Java Edition.

You can find them in the premium_cache folder, and under skins of your Minecraft storage directory, as above. However, they are encrypted.

There are however mods that allow the usage of higher resolution skins, but must follow standard model formats (means no custom models or parts), should you get them decrypted.

Edit: It is possible to get skins of this type through custom add-ons, which are basically the same, but obviously not store-bought.

Character Builder

First of all, this is a little more trickier. For most of the parts in Bedrock edition, they add extra geometry to your character. This means you can't directly transfer it to a Java Edition character. Instead, you'll probably have to recreate it using the textures, which are also found in the premium_cache folder, under persona.

How do I decrypt?

"Windows does not recognize this file format."

You don't. Or at least, you are not supposed to be able to decrypt them due to DRM. You could try recreating it from screenshots/eye.