If you are talking about an issue with the large chainring and the “smallest” cassette cogs (positions 1, 2, 3) my first thought is the FD cable has too much slack.
This does assume that everything worked fine at one time.
Shift to the small chainring and see how taut or loose the cable feels. If there is slack in the cable, simple turn the cable adjuster, if there is one on downtube/head tube, to remove the slack.
This may not solve other adjustment issues, but slack in the cable will not move the FD cage over enough. With chainring ramps and pins, it may still get the chain onto the large chainring instead of falling back down to the small chainring.
John