From the research I have done, the optimum 25(OH) vitamin D level for osteoporosis is 30-50ng/mL (75-125nmol/L). You want to adjust your vitamin D3 intake to get into that range which is typically around 1000 to 2000 IU/day.

Here are the footnotes for the studies if you want to look them up.
1 - https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional
2 - https://pubmed.ncbi.nlm.nih.gov/28722941/
3 - https://link.springer.com/article/10.1007/s00198-023-06802-x
4 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5471662/
5 - STOP IT Trial https://academic.oup.com/jcem/article/107/5/e1932/6504006