The new 690 Comfort Low will offer you a 9/16" (15mm) lowered riding height in comparison to the OEM seat height. Fits Models: (2021-23) 690 Enduro / SMC-R Non-North America Model Only. Note: Please look at seat base picture and compare it to your stock base. KTM changed the base in 2021 with no real break point.
KTM 690 Enduro R; Honda CRF450L; Used Suzuki DRZ400 Honda CRF250L Rallye; 2019 Kawasaki KX450. Spec: 449cc / 55bhp / 110kg / 955mm seat height; Price Being light and with an extremely lowI bought a Rally Raid RRP526 - 40mm lowering link. Seat is still a bit high but now the bike is manageable. Ktm are ridiculous when it comes to seat height. My 690 handles no differently with the lowering link. I am just about 6’ and weigh 196lbs.
That said, you’re not going to flat foot. I have a 29-30” inseam and I side saddle it. Left foot on peg, ball of right foot on ground, heel in the air like a dancer. Being 5’8” I’ve always had to sit like this and I’m used to it. If being flat footed is something you NEED, maybe a shorter seat (more money), lowering suspension (alsoHJmZZmf.