There are some companies working on that and / or there have been some experiments with it, but there's two factors there; the one is of course how much weight an aircraft can carry. The other one is the altitude and / or angle; a big plane goes to about 10 kilometers (maybe more, idk), but that's a 'flat' flight, ideally you launch while angled upwards and that's a bit more involved.
But that's how a lot of the X projects were / are done.
There’s actually been commercial launch services using air launch - Virgin Orbit, which went bankrupt, and Northrop Grumman’s (acquired as part of Orbital ATK) Pegasus, which hasn’t launched since 2021 and has one launch planned in 2026.