There are rubber freeze out plug replacements that once installed you use a wrench to tighten them into place. (quick and dirty fix)
No promises on how long it will last though.
The preferred method would be to install a OEM metal plug.
As to how easy or difficult, you’ll need to get your eyes on the area.
You say it by the motor mount.
If so.. you may need to support the engine with a piece of wood and a floor jack and remove the motor mount to gain enough access to R&R the plug.