My son has a standard 21" deep vanity and used the Kohler Archer sink in it. According to the specs the sink is:

19-7/8” (505 mm) x 15-5/16” (389 mm) x 7-1/2" (191 mm)

The sink fits just fine.

Here's a screen shot from their website

20.5" deep vanity box, 21.25" total counter depth. Used Lacava Spring sinks at 19 x 15 3/8 x 8 deep ... opening is about 15 3/4 x 12 at the end of the day with the negative countertop reveal ... worked fine. Very similar dimensions to the above poster.

Your sinks will fit easily. Relax, please.

21” vanities are standard....

I got 2 17 inch oval in my 21.5 deep vanity’s for 2 bathroom remodels.. The faucets are very tight. I didn’t realize this would be a problem and if I had known I would have gotten rectangle to save space in the back.