Latex \large use in matplotlib

How can I increase the size of \bullet and \blacktriangledown in matplotlib plot for additional text in the legend? I have

import matplotlib.pyplot as plt
import numpy as np

from matplotlib.pyplot import fig

... [functions]
plt.legend(['8 $\\times (x+y^2)$'], 
            title=$\\bullet$ syst. A \n $\\bigblacktriangledown$ syst. B, 
            loc='center left', bbox_to_anchor=(1.02, 0.5))
plt.savefig("05042022.pdf", bbox_inches="tight")

and if I use \bigblacktriangledown I get the error Unknown symbol: \bigblacktriangledown, found u'\' (at char 0), (line:1, col:1) and if I use \large, I get: Unknown symbol: \large, found u'\' (at char 1), (line:1, col:2).

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