Isuzu rodeo serpentine belt

i have a 2001 isuzu rodeo that i want to change the drive belt on however i cannot get the idler pulley to loosen. it has an automatic tensioner and the manual pictures using a wrench clockwise to move to “loose” position however i have used force on this and nothing happens afraid to use much more force and break something without confirmation of what to do to move this idler to loose position



It may be frozen (rusted) in place.

First spray penetrating oil on it and after letting the oil work overnight, (if there is room) give the bolt a sharp rap with a hammer to jar the rust loose.
Then use a power bar for good leverage.