Go to the trail head where you will be riding,
See what people your age are riding,
Ask them why this or that bike and where this or that Local bike shop Is...

I see big dudes like you riding fast and furious on all kinds of bikes, Hard Tails and Full Squish.

A thousand Is a good starting price for a Hard Tail that can get things done, $2500 Is a reasonable starting point for full suspension.
Below those price points and your going to want more bike after a few rides.

Big guys with some power/skills seem to do well on 29 Inch wheels but these big hoops need to be very good hoops for a rider your size,, spend a little extra coin and attention on your wheels......

Of course I am talking about real single track riding, not fire road rides....



The first picture was my beginner bike at $600, I quickly surpassed Its limits.
The second bike, a Scott Spark 760 retailed at $1900 I did the year end close out thing ($1500) and traded that first bike in on it,,,
Out the door Tax Included,,,$1280..
Had it one year now, still serves me well. time to replace the drive train, Hey I ride It hard,,, upgrading to a 1X11..

And yeah I clip In,,faster, safer, more fun,,,

https://www.youtube.com/watch?v=upwJaIlRJN0

https://www.youtube.com/watch?v=_qo8KyBNjBw