I could not tell from photos.
Compare redness of comb and wattles to known hens of same age. A roosters comb and wattles at 12 weeks will be best red. A hens comb and wattles don't turn red until she is laying, around 5 to 6 months old or older.
The rounded tail feathers look more like a female, but I have had roosters with rounded tail feathers at 12 weeks old. Look at the hackle and saddle feathers. If these have a rounded tip, hen. If long and pointed like an arrow, rooster.
Roosters have much smaller and many more hackle feathers than hens do.
There are some great YouTube videos on how to sex young chickens from hatch to 4 months old. If you compare redness of comb and hackle (neck) feathers on birds you know the sex of you will soon learn to tell the difference.