A tad over weight and looking for a mtb pant, not over trouser but a pant for cycling and bikepacking.

Ex Army goretex trousers maybe cut to 3/4 for wet weather. Likewise Army trousers or shorts. Well made stuff and so reasonable. Silverman’s is a good place for new military gear.
I’ve had some Ventile DPM trousers for over 20 years. Good stuff Ventile. Howies adopted it for a while.
If you’re flush, Fox make large sizes. Are we talking 40” waist or more? Maybe any US based brand will go proper large.
The Army surplus stuff always seems to be rather roomy.
Endura perhaps? Quite a range to go at there.
HIH
Neil

Keela roadrunners or scuffers

Decathlon AM pants for me and I’m a bit of a bifter!!

My endura pants are pretty generous in the thigh/butt area…

Work for my ‘Chris Hoy’ sized thigh beef.

If you’re not looking for waterproof, I’d give Rab Torque pants a look – they’re not bike specific, but I have several pairs and use them for pretty much everything from winter biking to dossing around the house. The cut is trim but accommodates my ‘ex-prop’ body shape, the knee articulation and fabric stretch don’t interfere with pedalling, and they have a zipped gusset at the ankle that lets you snug them up to keep them out of the chain.

Another vote for the Decathlon AM Trousers. If you can get them. May need to add a stock alert to the stock page.

https://www.polaris-bikewear.co.uk/Am-1000-Repel-Mountain-Biking-Trousers-p/pol01-5323-p.htm