are you saying you’re facing poor handovers due to poor coverage ? in such situation, the only solution is to enhance the coverage (antenna engineering). Ensure that the zones where there are HO are well covered (check the radio measurement statistics : average ul and dl rxlev)
Otherwise, poor HO are usually caused by interferences. Check BCCH/BSIC unicity, and cochannels, adjacent channels.
The poor HOSR occurs on all cells, or just few cells ?