So as what the title says, specifically, the crosshair needs to be addressed properly while aiming down on your weapons on warframes with bulky fashions. Take a look at this link: https://imgur.com/gallery/x3xIzqH
And here are seem to be links of related concerns whom have already voiced out before:
As for suggestions:
Either have an option in the settings that make your aim shoulder armor go invisible/fade while aiming (as what the other post have already suggested), so it happens regardless of what shoulder attachments players are wearing as long as this option is enabled.
Or have a radius around the aiming crosshair do an x-ray assist that can also be changed in radius effect. For reference to this idea, try playing V-Rising while indoors and notice how external elements that should have been blocking the view of your character while at a distant pan does it.
