Interfering in bullying behaviour is possibly not the best way to make things better.
If there is too much bullying going on its often because the chickens have not enough space and not enough to do. Maybe your perception of a large run with lots to do is not what is required for your flock. Especially when you have a few who are not the friendliest chickens. This often occurs within flocks with many different breeds and many different characters where the chickens who get bullied can’t get away and hide. (Out of sight is out of mind).
Bullying rarely occurs during the day with free ranging chickens and chickens who have a very very large run with bushes, herbs and grasses in it. Searching for food and taking sand baths keeps them occupied.
At roost time space and hidden roosts can do wonders too. Making a roost at the other side of the coop or room/roost divider is often a good solution to stop the bullying. Friends sleep together. The ones they don’t like get pecked. Nice if they can sleep elsewhere. A bit of fuss and pecking is normal.
Establishing and confirming a pecking order is normal chicken behaviour. Some pecking always occurs when you give them food. Having 3 feeders is great to avoid trouble. Throwing some scratch in the run is also helpful to keep hem occupied for a while.
If you can’t free range unsupervised because of predator pressure it might be possible to let the flock free range supervised an hour before sunset. They return to the coop by themselves after sunset. My chickens are so very happy if they are set free it really shows, and happy chickens don’t bully.
Natural rooster behaviour is to give the treats/some food to his hens. A good rooster doesn’t like it if you take over his job and may get angry with you if you interfere in his task. (Look for the article understand your rooster, written by
@Shadrach). I also wonder how old your roo is bc you are new to chickens. Under a year old he is a cockerel and might act like a teenager with lots of hormones going through his vains.