AutoCAD MEP 2024 toolset includes 2 kinds of snaps:
snaps that allow you to snap drawing points to geometric locations on other objects. For example, you can snap to the endpoint of a line, or snap to the intersection of 2 lines. There are 2 types of AutoCAD MEP 2024 toolset snaps: end connectors (often referred to as just connectors) and curve connectors. Use end connectors to connect new objects to the ends of existing objects. Use curve connectors to connect new objects anywhere along the centerlines of existing objects.
When you use AutoCAD MEP 2024 toolset snaps, the software inserts an appropriate fitting when needed, as shown in the following example of adding a pipe branch.

Snapping a pipe to an existing run using the pipe curve connector

Resulting branch with an inserted fitting
When you turn on AutoCAD MEP 2024 toolset snaps, they remain on until you turn them off. If the snaps are off when you use an Add command, the relevant AutoCAD MEP 2024 toolset snap is turned on only for the Add command. For example, if all AutoCAD MEP 2024 toolset snaps are off and you start the plumbing line Add command, the Pipe Curve and Pipe Connector snaps are turned on. Once you exit the plumbing line Add command, the Pipe Curve and Pipe Connector snaps are turned off.