lumberjacked

My suspension has Pedal Lock Out and Low SPD. When would I want to have pedal lock out and what's the advantage of the Low Spd settings?

I just upgraded from an entry level hardtail to a used carbon fiber XC bike I picked up for a steal. All the components are much nicer than what I had before. My goal now is to get fast on flowy trails. I'm not a gear head and mostly just want to have fun while exercising.

I'm relatively new to MTB. I bought an REI Co-op DRT 1.1 hardtail about 2 years ago. It's decent but I ride with guys who have full-suspension Santa Cruz or Cannondale bikes and they can manage to get up more tricky terrain. I find myself walking my bike more than I'd like.

I've seen some 6 or 7 year old seemingly better bikes on FB marketplace for $600-800 like a Ghost Kato FS 7

Is that decent upgrade from a hardtail while on a budget? What's the best options for upgrades under $1000?

It's mostly rocky hilly terrain and some gravel narrow tracks in central Texas.