None of the local telcos offer MBB devices with CA enabled, which is weird cause Zong and Jazz have had CA for a while now, but everyone still offers the same old Cat4 LTE devices.
So if you see any devices with Zong, Telenor or Jazz branding on them, you can be sure they don't support CA.
With that being said, I have seen some foreign branded (but unlocked) devices. Typically from Middle East or UK cause they use similar LTE bands as we do in Pak. Some of those do have CA, but not necessarily all the correct combos enabled. You'll have to test them with the carrier of your choice before buying.
I bought a Huawei B535-232 from Amazon UK (while I was abroad) and brought it back to Pak. Works perfectly with Jazz 4G+ (only tested B3+B8). It's been running for 2+ years in a rural area with an external antenna and it's easily able to achieve 50-60 Mbps during the day. If you can find one of those, I highly recommend it.