Technology

I believe that's very regional, if there's a local hiking club you could try to reach out to them.

There's often forums dedicated to hiking, which have all sorts of hikes mapped out.

But a map service like mapy.com (formerly .cz), has the official marked routes as part of their mapping data

I hike a lot and use Organic Maps, which is a front end for OpenStreetMaps. Far more detail available on OSM, plus you actually get to choose what's on display, rather than Google arbitrarily deciding that a road/track/landmark aren't important enough to mention.

A paper USGS topological map.

Perfect example of Google maps issue, is that we did Grampians on the weekend here in Australia. And, it still had a road/track which had been completely deleted (probably long ago). And it wasn't on any other maps.. There was a rusted sign that had been long removed and sawed off sitting where the route clearly used to be, but no sign of route anymore

These days, most people tend to just use AllTrails or Avenza because they're convenient. For Thru hiking (really long hikes), people tend to use products (apparently) like Captopo which better facilitate planning, tagging on long hikes and time calculations (I am hoping to do a thru hike soon).

In practice though, stolen untested routes used in Alltrails present their own problems though, as, the Alltrails team don't actually check if the routes are safe or correct. I suspect they just steal them from other sources. But, for most people, its great as its convenient

OpenTopo/Openstreetmaps are commonly used as the source for a lot of mapping systems though, as it tends to be up to date and accurate in most places. (i use it on my garmin etrex 32x as a backup). I was also advised to use Strava Heatmaps on a hike I am planning to do to find water in certain locations, however, I use GPX Map viewer Pro, and use people I trust for routes if possible (or make my own).

Google Maps is great for roads, but, the data simply isn't that accurate for anything else. And, there is no good way to report bad hiking routes. With OSM and other things, they can be fairly easily fixed

FTFA

Instead of Google Maps, Lions Bay SAR provided a list of free and paid hiking apps it recommends, including AllTrails, Granite, and Gaia GPS—which can be used as part of the process of properly researching and preparing for a hike or a trip into the backcountry