Do you mean a fillet that begins as a fillet with a radius of 7 and decreases down to a fillet of radius 3 (for example)? That's a 'variable radius fillet'. You can find it under drop down menu 'Insert->Dress-up Features->Variable Fillet', or on the 'Dress-up Features' toolbar (the fillet icon is a flyout icon with 4 different fillets available).
And you can use the "Variable Fillet" command to create fillets of different (constant) radii on different edges on your body too, pretty much the same way as in Catia 4.
