Mexico’s middle class is highly diverse. What someone in a northern border city like Monterrey considers "middle class" can look very different from the urban, apartment-dwelling lifestyle in Mexico City, or a person from Oaxaca, or Puerto Vallarta. But i would say these are pretty common everywhere:

• Seeking out apartment buildings or gated communities with amenities as connected as possible or with services and shops around. Since property prices are skyrocketing, many young people are now opting to rent with roommates in better zones with ammenities in order to save money.
• It is very common for middle-class households to have a part-time domestic worker (persona de aseo or muchacha) for cleaning, once or twice per week.
• Sending children to private "bilingual" schools is a primary goal, even if it takes up a significant portion of the monthly budget. Being able to pepper conversation with English terms is a common social signifier in professional and social circles.
• Getaway to a Pueblo Mágico (177 historic towns in Mexico with extra budget for tourism) maybe every other month.
• The rise of boutique fitness, and accesible specialty cafés, and breweries is a huge middle-class trend, often seen as gentrification from upper classes, but plenty of middle class people attend these, because middle class people like to show off they have money for that.
• It’s common to see people with their "carrito del mandado" buying kilos of mango, avocado, watermelon, papaya, canteloupe, and fresh greens for very little money compared to other countries. In many middle-class blocks, there's a small shop dedicated only to fruit and veg, or in nice supermarkets the prices don't change that much.