Do Lexus vehicles always tell you whether or not the hood may be open or not? The car doesn't give me any disclaimer to tell me that my hood may be open. Would it be worth it to invest in a new hood latch?

 

There is a 2 part latch. When you pull the lever inside the initial one releases and the hood should pop up about an inch. That is your telltale that the hood is open. The secondary latch should prevent it from flying up and hitting your windshield. You then reach inside to move the lever and release the hood.

A new latch will not help if there is a hood loose sensor and that is defective. I doubt your old latch has anything wrong with it, most of the time a little spray lubricant is all they need. Unless you were in an accident it should last the life of the car. I would take it to a body shop as estimates are free and they can tell you if anything is wrong.

The owners manual will provide information regarding whether there is a warning light. Here is a copy attached. I did not notice anything regarding a loose hood warning.

If want to see all the owners manuals you can find them online at the Lexus Drivers Site. Link is below. Join for free then enter your VIN to see the manual and also it provides the dealer service history.
https://drivers.lexus.com/lexusdrivers