Post covid many bike companies were in big financial trouble so new bikes cost less than used, but that's mostly resolved or the companies are just plain failing, so definitely look for a newish (aka few years old) used bike and you'll get a lot more for your money. Manufacturers are all pushing ebikes (with electric motorcycle specs) these days and now 32" wheels (don't get me started - and I'm 6'5") so depending on your planned riding and budget 29" HT or full-suspension mountain bike (off-road, trails, casual), or hybrid style / gravel (light off-road, commuting, touring). Focus on a known brand, quality basics (in the order of (frame, fork, wheels, drivetrain, brakes) and figure it out from there. Avoid cheap versions of ebikes, full suspension or carbon; there's typically good reasons for the price and usually you can't fix or upgrade them - although the Walmart Ozark Trail is a decent attempt (but still has major short-comings; you're better with something like a Polygon HT).