What are the normal heights of PCI-express cards?          

First off there are no real spec. limits on card  length, some huge GPU cards are 12" long and more at 10" ! and best are 6" (GTX1050 prime examples of short good cards)
There are also double and triple wide cards, for sure seen on GPU with HUGE heat sinks, only you can measure what fits in to any of 10,000 cases made. (only you)
There are basically 2 heights (and 1 pitfall, told later)
Next, there are 2 heights to consider the J-bracket (my name) or as others call it the Hockey stick bracket, full height 120mm or 79mm , a.k.a. full height and 1/2 height (or low profile).
Next is the actual card (pitfalls) the card is 69mm  or 111, but some cards , yes, pain, have these huge cooling tubes (GPU power hogs)  on top that hit the case lid of my Dell T3610.
This great graphic drawing below shows,  the variances ( J bracket and card both) A very nice mechanical drawing here. Note Zero Carbon squirrel-fox?.(caged)

This is ATX PCI spec, version 1.: ( EXPRESS CARDS)  For sure many cards exceed this length. For  Sure GPU cards with 3 full fans on board. (yah) X16 is GPU.slot.
The length below is really silly, if you consider the huge numbers  of cases types sold.  Some have 15 inches front to rear and has GPU card holder on the end. (yah, silly) But height really does matter most.
Some Towers can do 19" 503mm GPU ! (proof at Newegg  for  Phanteks Enthoo 719 (my 3020 does 10" inches, not cutting out HDD cage as many do)

If buying 
a low profile 79mm card,  and it is a GPU card, (some ITX cards excepted) do expect that you will  be limited on performance of those cards  lacking space for full heat sink sizes , for  sure.
But any GTX1650 will run at full speed what ever card you chose the problem comes up with over 75watt cards some go to 200watts, or  even MORE.
1/2 height cards if fast may need more fans, but there is no space for more fans here and must scream the 1 fan super fast RPM and huge noise results.
Buy full sized PCs to you can game at full speed.(with real GPU cards full sized and full speeds) and way way less NOISE.
Buy cards with huge fan (diameter) that runs slow, or even not at all until 50C temps are reached. (noise matters, to many folks so there you have some facts)

MOBOs. The first 3 matter,  as others have no PCI-e slot or no x16 slots. Note that most double wide GPU cards would fail and hit the case bottom with mini-ITX. (only looking first matters)
Worse is some GPU cards used on  lame, Micro-ATX hit the DDR RAM slots, or block SATA cables.
 (  BTX , it is DEAD now and never  pay good money on any BTX here is why.)
 (oh and the whole shebang)

This page above answers some questions like will my new CARD FIT and not HIT things in my PC, answer only looking and using a ruler works!!!

Behemoth 1: (Johnny noob says, will this fit my ITX?) then cuts the case open to fit (hacksawed) and then blows up the PSU.

Will this fit? , sure

version 1.  11-9-2019