Truck will not start

Battery checks out at 11.95vdc but when I push button, only here clicking noise? Truck is a 2018 Tacoma with 50,000km on engine

 

that's awfully low, I think it needs to be around 12.6. I would get the battery load tested after a good charge. Low mileage isn't necessarily any indication, as they have greatly varying lifespans. Short trips, infrequent use, hot and cold climates have a great affect on lifespan.
How old is the battery? I don't normally just guess and swap parts, but in this case, if it's older than 36 months, I'd just replace it.
Look at aftermarket doodads and wiring modifications. They may be discharging battery while not in use.

 

What is the voltage when the engine is cranking over?

 

Sounds like you're getting a new battery....

 

Charge it and don’t give up on it just yet.

Do you have any aftermarket electrical components that might be drawing juice?

 

Piling on here with another battery vote.

Use your DVM while someone else trys to start it. Bet it drops like a stone.

 

31k miles is very low for an '18. Sounds like alot of short trips or sitting, both of which are not great on the OEM battery. Get an Odyssey or similar AGM battery for better lifespan. Doubt its a starter at this point and likely not the alt not charging with that low of miles on the engine.

 

Five year old battery? - I'd replace it whether you need it or not -
Pretty chilly in Canada 'eh ?...
Pretty hot in the desert SouthWest... we get 2-3 years out of ours.