Yes, its the value under loot_chests->quests->[]->base here:
https://api.splinterlands.com/settings
I've previously used the following function to calculate how many chests you get for x RP in different leagues: (The function returns five arrays (one per league) with the thresholds for various amounts of chests).
def getQuestTotalRPTresholds():
max_chests = 30
quest_bases = [390, 6500, 22500, 53750, 112500]
quest_step_multipliers = [1.2, 1.13, 1.09, 1.062, 1.038]
quest_chest_limits = []
season_chest_limits = []
chests_increments = [a*b**np.arange(0,max_chests+1) for a,b in list(zip(quest_bases, quest_step_multipliers))]
total_points_chest = np.cumsum(chests_increments, axis=1)
return total_points_chest