the files will be downloaded in chunks into memory.
by default, rclone mount does not use a local file cache
i have a summary of two vfs caches
idrive continues to play a game, first year low price, second year price increases by a lot.
at one time, i have 5TiB with idrive, but they kept raising price year after year.
for many years, i push old backups, that i never plan to need, to aws s3 deep glacier at $0.99/TiB/month
and hetzner storagebox, imo, the best overall storage option.