Thank you guys; took the project to the end with your guidance.
I had a big matrix written in an Excel file and I wanted to access different parts of it using Arduino. Arduino shouldn't have been connected to the computer, therefore, I chose to use a micro SD card.
Utilizing the SD library, I could read .txt files easily but not my Excel file.
The answer to my main question "MicroSD; read from anything else than .txt?" is Yes. There are some libraries like the one @markd833 mentioned:
It did read the CSV file but I could not get the hang of it easily and didn't have enough info about how to change its source code. It read my CSV file but I couldn't read a specific cell out of it.
Also, @cattledog informed me of the SPIFFS file system in ESP32 which seems pretty suitable for storing my data but I didn't have time to learn about it for this project; I just used the SD card this time.
Anyways, I decided to convert my Excel into a .txt file as my data were all two-digit numbers and were distinguishable if in a text manner. I divided my Excel data into sections for ease and stored them in almost 300 .txt files on the SD card. I read file1 and stored the small data from that file in a Matrix on the Arduino(ESP32) and did what I wanted to do with that, and read file2 and rewrote it on the same Matrix to do my job with that data, and so on.
I didn't explain what I wanted to do with the data as I thought it would just over define my problem.. They are HH, MM, and SS data of some different happenings of 170 points of an area and I compared them to the current time so that I would know which one is happening now. (Or maybe it would let you tell me a way better way to do this!)
But it's all working now and I'm greatly thankful. Best wishes.