Hi @wegosi you can use following codes inside child theme functions.php or bp-custom.php
You can change the values as per your requirement
if ( ! defined( 'BP_AVATAR_THUMB_WIDTH' ) )
define( 'BP_AVATAR_THUMB_WIDTH', 50 ); //change this with your desired thumb width
if ( ! defined( 'BP_AVATAR_THUMB_HEIGHT' ) )
define( 'BP_AVATAR_THUMB_HEIGHT', 50 ); //change this with your desired thumb height
if ( ! defined( 'BP_AVATAR_FULL_WIDTH' ) )
define( 'BP_AVATAR_FULL_WIDTH', 260 ); //change this with your desired full size
if ( ! defined( 'BP_AVATAR_FULL_HEIGHT' ) )
define( 'BP_AVATAR_FULL_HEIGHT', 260 ); //change this to default height for full avatar
