you can take your battery out and take it to an auto store, but IMO getting the battery out is a paint. I would recommend a tester, I got this one and I thought it worked pretty well, but there are others on the market. IMO aside from a good charger, and a multi-meter it is probably one of the more useful diagnostic tools to have for a motorcycle.
You either need to purchase a battery load tester (like this one) or remove it and take it to an automotive or battery store, testing the voltage is not enough to tell if the battery is in good condition since it can show 12 V but not have enough current to turn over the starter. You should also check if the battery is grounded properly.
The voltage test in the picture can be useful but doesn't always tell the whole story.
Since I have a couple of cars and am always helping out friends with theirs, I picked up one of these load testers: https://smile.amazon.com/ANCEL-Battery-100-1100-Automotive-Analyzer/dp/B07Q6NBXQG/ref=sxin_16
That will tell you straight if the battery is not up to par. Alternatively, you can get it load tested at most parts stores for free.
Batteries typically last about 3 years, you can extend the life if you use a trickle charger or remove the battery during storage. I would recharge the battery to 100% then take it to a Auto parts store and have them do a load test, you can also buy one as well. I have this one and it works pretty good.
Start with the battery and if that doesn't work you can start checking other stuff like switch continuity, fuses & starter relay & ground connections.
I literally just did this with my own bike so if you have any questions shoot me a PM.
I just had an issue that was like this. Things I would check.
My Issue ended up being that the ground stud was loose, I did replace the starter relay as well as the resistance was outside of range.
thorough flowchart.
I wonder if those battery load testers would be a better option to evaluate 12v battery condition, especially if a relatively new battery is discharged and the car hasn't been driven for several Covid months.
Otherwise, 12v batteries are cheap compared to other car repairs. It would not hold me back on a purchase.