The link that Rich supplied talks of FireWire to Thunderbolt adapters.
You may already have the 4 pin to 9 pin FireWire cable.
The FireWire to Thunderbolt adapter is this at around $29 or£29.
https://www.apple.com/shop/product/MD464LL/A/apple-thunderbolt-to-firewire-adapter
As your Mac has USB C ports then you will need yet another adapter, a Thunderbolt to USB C adapter at around $49 or £49.
https://www.apple.com/shop/product/MMEL2AM/A/thunderbolt-3-usb-c-to-thunderbolt-2-adapter
As far as I am aware there is not an adapter that can go straight from FireWire to USB C so there will be 3 cables in all from cam' to Mac.
Importing mini DV into recent Macs seems to be met with varying success. Some say it imports with no audio and some say no video or audio. Having to use 3 cables can't help either.Some have success.
Trouble is that you won't know until you have spent around $80 or £80 for adapters.
Jan, above, mentions using an older Mac with it's own FireWire ports.
Not only that but the older OS's and older versions of iMovie seem to handle the import of mini DV more successfully .
If you have access to one then import into it and then transfer footage over to your new Mac.
If you do have access to an older Mac ( yours or a friends) let us know the details such as model, OS and iMovie version and we may be able to offer more help.