The thing that catches people out with leather trousers is sitting down. They feel fine standing in the changing room, then you sit at a desk or in a car for twenty minutes and realise the pair you bought has no give at all, and you spend the day tugging at the knee so you can bend your leg properly. A bad pair genuinely limits how your day goes. A good pair, in proper leather or a decent faux with some stretch woven in, moves with you and you forget you've got them on by lunchtime, which is the whole point and why it's still worth the search.
They're not the right choice for anything that involves a lot of walking in the heat, or a day where you need to get changed quickly in a cubicle with no chair, because the tighter ones take effort to get on and off and you will sweat doing it. Sizing is the other trap. Leather doesn't behave like denim, it doesn't have the same forgiveness, so if you size down expecting them to stretch out the way jeans do, you'll spend the evening with a red line across your stomach and regret every poppadom. Go for your normal size or even up if you're between, and check the back of the knee and the seat specifically, because that's where cheap leather creases and goes baggy within a few wears while better quality holds its shape. The waistband is the other fit problem, a lot of pairs gape slightly at the back even when the hips fit, so look for ones with proper shaping or a higher rise rather than a straight cut waist. The difference between a flimsy pair that creases like a crisp packet after one sitting down and a pair that still looks sharp a year later is usually exactly where you'd guess, in the leather itself and the lining, and it's worth paying for that even if it means buying fewer things that month.
They clash with anything else that's shiny or stiff, a leather jacket on top of leather trousers reads more stunt double than outfit, and heavy structured bags fight them rather than sitting well against the material. Soft knits, plain shirts, something with a bit of slouch up top, that's where they actually look like clothes rather than a costume.
Try sitting down in them in the shop before you decide, not just standing in front of the mirror, because that's where the real fit shows itself.