It honestly depends on the rooster . They may need some time to get along, I recommend raising males together from a young age. And silkies are actually the normal size of any other chicken, though the Bantam Silkies are much smaller. Bantams have no "Quiet Crow" Exception though. My Buff Bantam Silkie Rooster has a loud little squeaky crow. Kinda sound like someone stepped on a squeaky toy to the cock-a-doodle-do tempo.
Silkies are known to be docile anyway, but there have been a few instances where silkie males are quite aggressive.
If you want multiple roosters, I recommend rising them around eachother, and with the hens they will breed with (also raised from a young age if possible)
I was getting 6 Thai spring!!