FabricTPA

A server-side Fabric mod that adds /tpa command-set.
Works for Minecraft 1.16.2+ (snapshots not fully tested)
Requires FabricAPI

Provides the usual set of TPA commands: /tpa ＜player＞ - Initiates request for you to teleport to ＜player＞
/tpahere ＜player＞ - Initiates request for ＜player＞ to teleport to you

/tpacancel [＜player＞] - Cancel a tpa or tpahere request you've initiated, argument required if multiple ongoing
/tpaaccept [＜player＞] - Accept a tpa or tpahere request you've received, argument required if multiple ongoing
/tpadeny [＜player＞] - Deny a tpa or tpahere request you've received, argument required if multiple ongoing

More info over on GitHub