Model number doesn’t appear on the apple official web site

That's an iPhone 12 Pro Max, 512 GB, Blue.

The US model model equivalent is MGDL3LL/A. The LL means a US/Canada model and /A means revision A. The TA/A at the end means Taiwan revision A.

Apple no longer lists the iPhone 12 Pro Max on the Apple bands website because the model is no longer sold after being superseded by the iPhone 13 Pro Max. It should be model number A2411. It gets confusing because they have two model numbers including the one that may be printed on the case. The data looks like it's only for making decisions for buyers of current models.

https://www.apple.com/iphone/cellular/

But the information is available from the Internet Archive's Wayback Machine if a date is selected before the iPhone 12 Pro Max was discontinued about mid-September 2021. This lists the bands from the Sept 1, 2021 archived version of the webpage. Scroll down to Model A2411. There's a long list of locations including Taiwan.

https://web.archive.org/web/20210901123640/https://www.apple.com/iphone/cellular/#iphone-12-pro-max

iPhone 12 Pro

Model A2407

iPhone 12 Pro Max

Model A2411

1 (2100 MHz)

n2 (1900 MHz)

n3 (1800 MHz)

n5 (850 MHz)

n7 (2600 MHz)

n8 (900 MHz)

n12 (700 MHz)

n20 (800 DD)

n25 (1900 MHz)

n28 (700 APT)

n38 (TD 2600)

n40 (TD 2300)

n41 (TD 2500)

n66 (AWS-3)

n77 (TD 3700)

n78 (TD 3500)

n79 (TD 4700)

1 (2100 MHz)

2 (1900 MHz)

3 (1800 MHz)

4 (AWS)

5 (850 MHz)

7 (2600 MHz)

8 (900 MHz)

12 (700 MHz)

13 (700c MHz)

17 (700b MHz)

18 (800 MHz)

19 (800 MHz)

20 (800 DD)

25 (1900 MHz)

26 (800 MHz)

28 (700 APT)

30 (2300 MHz)

32 (1500 L-band)

34 (TD 2000)

38 (TD 2600)

39 (TD 1900)

40 (TD 2300)

41 (TD 2500)

42 (TD 3500)

46 (TD Unlicensed)

48 (TD 3600)

66 (AWS-3)

https://support.apple.com/kb/SP832?locale=en_US

Go to apple.com > Support, then type "1phone12 pro max specs" at the spyglass (search symbol). A list of internal (archived) Apple document-links is presented.