I'd second the opinion that this forum has a lot of excellent information on it, and a good search function that turns up all sorts of threads. Over the years I've found great instructions to many places such as Ratatat, the Stinson site and Mount Superbus.
Some of the online wikiloc sites and apps such as Alltrails are useful, but need a fair bit of caution if you're planning to go off the beaten path. Anyone can put a trail up without any guarantee that it's 1. a decent route and 2. across publicly accessible land. I usually compare them (and trails out of older guide books for that matter) with QTopo to check that I"m not going to end up in someone's backyard and/or drug plantation, because it's a fair guess that the someone won't be happy to see me
. As a person who generally walks solo, I like to avoid in-the-field confrontations. This may not be a big issue around Mount Glorious (I'm not super familiar with it) but it's an increasing problem in Main Range and the Scenic Rim. As with all social media sites, generally the comments give some indication of the quality.
Parks, the State mapping departments and other official map authors gradually stopped putting unofficial trails on their maps in the 1990s, due to caution about being sued by people if they used them and had a mishap. AFAIK Alltrails etc get around that with the standard social media "we're just providing the platform, not the info" disclaimer. These days I think there's also caution from Parks et al about encouraging the teeming hordes into environmentally sensitive areas, particularly when you see what the teeming hordes do to the accessible places.
Anyway, TLDR: this site's archives are good. Alltrails is good but caveat emptor.