If you backup WeChat to a PC, the backup file is located in \LocalCache\Roaming\Tencent\WeChatAppStore\WeChatAppStore Files\username2\BackupFiles
or C:\Users\username1\AppData\Local\Packages\TencentWeChatLimited.forWindows10_sdtnhv12zgd7a\LocalCache\Roaming\Tencent\WeChatAppStore\WeChatAppStore Files\username2\BackupFiles
Or
C:\Users\USERNAME\Documents\WeChat Files .