How to transfer contacts from dumb phone to dumb phone

I have a samsung keystone 3. It's a bit primitive, I know-but I like being disconnected from social media, makes life easier and less dizzying. Anyway I store my contacts on my phone as my SIM only lets me have one number per person (perhaps it's just the sims in my country, or are they all like that?) I'm getting a new dumb phone, and although I can technically transfer my contacts to my SIM and from there into my new phone, when I do that it only records one number from each contact, making me manually go through them to fix it and add numbers.

Is there anyway I can do this easier? Perhaps copying the contact files (through my computer) and pasting them in my new phone? (A Nokia 20 Would that work?

Thanks in advance!