In Resilio I Share > "Copy to Strongbox". I mark it as Read Only to keep from confusing myself and use a separate "Mobile kdbx" for any passwords I create on Mobile and share that the other direction as needed. (I don't have to use two files, I just find it an easier process that makes it less likely for me to forget to sync one direction or the other and "lose" a password.)

(I miss Windows Phone here in that I could directly share my Resilio file and its sync status with a KDBX app as Resilio was a standard file host. iOS really should standardize something like that instead of forcing a unidirectional Share as the only pattern.)

(ETA: I tried Files which is supposed to do something closer, but it didn't seem to work for me.)