I'm surprised there isn't one already? I know there is a freeware Amsterdam-Rotterdam but you need 22 other files are are mostly no longer available. Plus i see when you do have everything it still barely works. Or Amsterdam - Antwerp
There is one Dutch route that is Payware that comes with all the loco and stock https://www.trainworx.nl/product/retro-canvas-route/ There are a few Freeware Routes for Holland and Belgium but you need other routes and stuff to make them work And Belgium
You have this website for payware Dutch routes for Train Simulator 20xx by what can see on screenshots the quality it's not perfect but ain't terribel either so always worth having a look at https://trainsim.hcc.nl/hcc-trainsim-add-ons.html