I can see what looks like lice eggs in the feathers. You should be able to part the feathers on her skin and under her vent and see tiny fast moving tan bugs. Permethrin liquid spray or dust is good to use for both lice and mites. The permethrin concentrate (about $10 at TSC for a pint) mixed with water according to package instructions, and used with your own spray bottle around 1/2 ounce per chicken is good. Here is a good link that shows lice eggs and what to look for: https://the-chicken-chick.com/poultry-lice-and-mites-identification/
Yes, looks like lice! The white clumps are nits (eggs). You will need to treat her, your coop and bedding for lice. Would be a good idea to treat the whole flock.
You can use a Permethrin based poultry spray or dust. Spinosad is also supposed to be effective as well.
Others may have suggestions about what they use and what works for them.
Check with your local Tractor Supply, they carry a wide variety of products that can be used.
I'd do the Permethrine as advised above. If using liquid or powder...I put it on the skin of back of neck, under wings and around vent. Make sure you are getting the skin. I always retreat in 5 days then a week after that.
If using the liquid concentrate, mix it according to inside package instructions for chickens. Usually it is 1/2 ounce or 15 ml per gallon. Spray the areas where the lice and eggs are found. Repeat in 7 days to get newly hatched lice eggs. If using the permethrin garden dust sprinkle it on the chicken, avoiding the eyes with either dust or spray.
The lice eggs will be attached to feather shafts and might be difficult to remove. Apply coconut oil to remove them. Inspect ALL your birds for lice and mites, especially around their vents where it's warm and moist.
Avoid their eyes when applying permethrin. You can put a little permethrin dust on your fingers and gently rub it on her face/wattles.
As mentioned, you'll have to remove bedding from their coop and dispose of it, including nest box material. Clean the coop, then either spray or dust everything inside the coop including nest boxes and roosts. Then put in new bedding. I recommend that you lightly dust the new bedding with permethrin powder, then 'pat' it down.