transferring data to a new iMac

I want to transfer all the data from my old iMac circa 2016 to my new iMac. Ive got the assistant up and running using an ethernet connection with 5e cable but it says it will take 62 hours, which I don't have. the old iMac only supports thunderbolt 2.0 and I can't seem to find any such thunderbolt 2 to thunderbolt 3 adapter locally. is there some way to speed up the data transfer so it could be done in under 12 hours?