In LTE, getting Rank4 percentage around 5% is normal?
I understand the more the better but honestly I’m not familiar with those values in my network
It is ok to get rank 4 cluster wide between 5-10%.
In dense urban rank4 is higher.
Do you think that downtilt antenna can get higher ranks because of higher posibility of multi-path?
Yes, I think that implementing more downtilt will contribute to richer multipath due to reflection with the ground (not just line of sight path). Some vendors recommend at least 8 degrees downtilt for NR for a higher rank.