Yes, the multiplier does include risk and reward.
A multiplier works in the same way as decimal odds. It tells you how much your stake will be multiplied by if your entry wins.
For example, a multiplier of 3x means that for every $1 you bet, you will receive $3 in total if the entry wins.
Important information
3x multiplier is equivalent to 3.00 in decimal odds, and +200 American odds
A $10 wager would payout $30 in each odds format
Win $20 (Reward) + $10 stake (risk) = $30 payout