Is link bracelet 42mm compatible with Apple watch SE 40mm?

In short: No, a 42 mm Link Bracelet is not fully compatible with the 40 mm Apple Watch SE. Here's why:

Apple categorizes its watch sizes into two bands of compatibility:

• 38 mm / 40 mm / 41 mm watches share interchangeable bands.
• 42 mm / 44 mm / 45 mm watches share a different, separate set of bands.

That means a 42 mm band—like the Link Bracelet—is intended for use with 42 mm, 44 mm, or 45 mm case sizes, and not the 40 mm variant.

According to the fine print in the detail of that watch band, it looks like it should fit.

38mm, 40mm, 41mm, and 42mm bands are compatible with 38mm, 40mm, 41mm, 42mm case sizes. 44mm, 45mm, 46mm, and 49mm bands are compatible with 44mm, 45mm, 46mm, and 49mm case sizes.

But you can get retail help using the link below.

https://contactretail.apple.com/Help

Please keep in mind that you will have 14 days to return it if it does not fit.

The answer will depend on the specific Apple Watch band. When you purchase them from the Apple Store or most third party sellers, such as Amazon, the band will specifically tell you which size watch it will fit. Which band are you considering?