I faced this when I moved an old contact backup to a new phone. The number of vCard contacts in the VCF file was large enough to make the phone import stop before adding all the contacts.
First, make a copy of the original VCF file. Then try opening it in Google Contacts or Outlook Contacts. If it loads, you can create smaller contact groups and export them as separate VCF files. This free method works sometimes, but with a very large contact file it may become slow or skip contact fields like phone numbers, email addresses, notes, photos, and address details.
In my experience, dividing the larger VCF file was more appropriate. I used the Softaken Split vCard Pro since it provided me with a preview before dividing it into smaller files.
If you will try this tool you can easily break your large VCF file without losing any details and without needing internet access. In my opinion you should try it first.
Tip: import one small VCF file first. If contacts look fine, then import the remaining files.