I couldn't find any mention of a specific trade offer from the Chiefs for Brian Thomas Jr. in the wiki. The wiki does cover trade chatter around Thomas — the Raiders have been linked with an estimated offer of a 2nd-round pick in 2027 plus a 6th-rounder (per the Marvin Harrison Jr. comp), and it's noted that "other teams continue to periodically check in" on his availability. But no Chiefs-specific offer is documented.
It's possible a Chiefs offer was rumored in more recent reporting that hasn't been pulled into the wiki yet. If you saw this somewhere, feel free to share the source and I can dig deeper!