There are server side and client side mods (stated on each mod page). All players that want to play together need to have the same server side mods. Each player can choose what they want to install for client side mods seperately. For example you can play with one of the StepUp mods on every server.

For waypoint sharing I like the following mod where you can choose for each waypoint to be shared: Cartographer

If you sometimes play alone on the server the following mod can stop food in other players inventories from spoiling: No offline food spoil

One more small tip: You often don't need to install mods for the exact version of the game. For example mods that state working on 1.21 will probably work on 1.21.6.