I've used two Dell U2412M in landscape at home for years, and had dual monitors for quite a while at w*rk before I retired 16 years ago. Two should be a minimum!
A year or so ago I added a Dell U3219Q 4K as my main monitor and rotated the two smaller ones to portrait and had them off to the left side. One of the 24s started an intermittent failure mode a while back so I parked it until I can dispose of it and rotated the remaining 24 back into landscape.
It isn't difficult to get the two sizes to display text at the same size so dragging across screens works well. Mostly, the big monitor is the main monitor (CAD, graphics, spreadsheets, browser) and the secondary monitor has multiple file manager and notepad windows open.
The U3219Q is very nice, but the prices are not coming down so it has been easy resisting buying another one -- just because it would be cool.
An important thing to keep in mind is your video card. I've got a Quadro P2000 which will run 4 large monitors if needed, and it had no difficulty running the large one and two small ones. But I don't do gaming and that's a CAD type of graphics card, so I can't address how things would work for a serious gaming setup.
Also keep in mind that a small high-res monitor may have a native resolution that makes text very tiny. I've always scaled text to a good size to reduce the eye strain, but then my eyesight has never been great. The 32" monitor lets me have plenty of screen space even with adjusting the display size to make things easy to see.
If you are going to be spending significant time at the computer, lots of screen real estate is very nice to have.