Samsung will unveil the Galaxy S21 series on January 14, which will become available in Western Europe on the 29th, according to documents obtained by WinFuture. The intervening period will be reserved for pre-orders.
Those who pre-order the Samsung Galaxy S21 Ultra will receive the new Galaxy Buds Pro for free (which will cost €230 when sold separately). The Galaxy S21 and S21+ will get the Buds Live instead (these were €170 at launch, but can be had for under €120 now). Every S21 pre-order will also net you a SmartTag Bluetooth tracker (this accessory will sell for €30).
Source (in German)