The documented way to export contacts from Google Contacts for importing to iOS is well-described in this simple Google article. It will walk you through selecting contacts on a Web page to choosing an appropriate export format. The one to pick if you're moving contacts to an iOS device is the VCF file format which contains VCard data.
Once your VCF file is ready, there are a number of options to transfer them somewhere else.
If you want to instead add these to an iCloud account and you don't have MacOS (for example, you wish to make these contacts available on an iPhone without connecting your iPhone to the Google account that had those contacts), you can also upload the VCF file to iCloud. From your iCloud Contacts page, while logged into the iCloud account, use the "+" button and choose to "Import Contact". You can then upload the VCF file that google created. This import approach will create duplicate contacts in your contacts account, so if you think you may have duplicates and you do have the MacOS Contacts.app, that approach is preferable.
Any time you find that you've got addresses available on Google Mail but they're not available in your MacOS Contacts, the Google export --> open with Contacts.app process is quick and won't flood your contacts db with duplicates.
The VCF file with VCARD entries is a widely-accepted Internet Standard, so it may also be appropriate for importing into other destinations.
The source code (markdown) for this article can be found on GitHub.