I mod it so I can be one shot and so can human enemies. If I get hit with a shotgun instant death, if they do instant death. It keeps you on your toes to know even 1 mistakes can mean you are dead.
I also mod it so ammo is very rare, you are never stock piled with ammo. It is not uncommon for me to never have more than 10-20 bullets. Make those shots counts, judge engagements carefully.
Stimpacks are nearly non existent, broken limbs severely impede you etc
Certain enemies are more "bullet spongy" within reason and this makes the game harder because whereas they can potentially one shot you you can't them. Robots for example unless you are using an EMP weapon take many shot from ballistic weaponry, Ghouls take numerous shots the the torso (only one to the head, rewards aiming), Deathclaws take a few due to their thick armor plating etc
Legendary enemies should have unique loot, unique appearances, unique lore etc. Not just a sponge that absorbs 100 bullets as I fear they will be