What will be the product ratio if I do chlorination of p-toluic acid?
I couldn't find any literature evidence for the nuclear chlorination reaction of 4-methylbenzoic acid (p-toluic acid). Instead, I found a patent in Japanese for the nuclear chlorination of 4-methylbenzoic acid chloride, of which, I believe close enough to your question (See below the translation given in Google).

According to the patent, when mixture of 99.7% pure 4-methylbenzoic acid chloride ($\pu{927.6g},\; \pu{6.0mol}$) and ferric(III) chloride ($\pu{2.9g}, 0.3 \:wt\%$) was heated at $\pu{50\!-\! 55 ^\circ C}$ for $\pu{22 h}$ in the presence of $\ce{Cl2}$ gas. After completion of the reaction, 84.9% of 3-chloro-4-methyl benzoic acid chloride was isolated. In addition, 0.1% of 2-chloro-4-methyl benzoic acid chloride and 2.2% of dichloro-4-methyl benzoic acid chloride were also isolated (dichloro-4-methyl benzoic acid chloride was not identified, but it should be 3,5-dichloro-4-methyl benzoic acid chloride, judging from the ratio of 3-chloro-4-methyl benzoic acid chloride to 2-chloro-4-methyl benzoic acid chloride). 



Reference:

Inventor: 智規 加藤亮太 甲斐幸基 小林, "Isopropyl 3-chloro-4-methylbenzoate and method for producing same." Patent application # (2013): WO2013015203A1 (https://patents.google.com/patent/WO2013015203A1/en).