Spring 2021 reopening?

I want to plan a trip between Feb-March or Mar-April but since this pandemic it seems airlines are not covering Covid related incidents for the future. Is there some sort of guaranteed refund if things go south or are people relying on hope when purchasing tickets as of late?

Covid-19 is a known risk, so that factors into things like insurance/cancellations. You should get travel insurance anyway for things that are unexpected - people still get sick.
The unknowns are things around how quickly elements like quarantine restrictions are lifted, access (visas/entry requirements), and restrictions on returning to your own country.
Some places will open up more rapidly than others, and it is looking like it will be a bi-lateral set of arrangements.
Japan lifted its state of emergency, but the borders are still effectively closed.

Honestly, I think a lot of people are just not buying tickets.

I know in the USA if you buy a ticket directly from a US airline and the flight is cancelled you are owed a 100% refund even if said ticket was non-refundable. Things get more complicated through flight aggregator sites and you then need to fight said 2nd party to get your money.

You'd need to look at the transportation bureau or department of whatever airline you wish to fly mandates on cancelled flights, if you buy direct from that airline. If the flight is not cancelled and you just can't use it... you'd need to have bought travel insurance that covers all possible cancellations (and yes, I bought some for my February 2020 trip and specifically looked for insurance that would let me cancel for any reason, I did not cancel and went to Japan right before a lot of things started to close,)

My MiL was supposed to take Delta (along with some partner airlines) to Israel this May for some sort of tour of Israel and Jordan. She got her airline tickets completely reimbursed via Delta.

For hotels, just don't book non-refundable. That's pretty simple. Most of the hotels I booked allowed me several days of cancellation before check in which would have been perfect had I needed to cancel.

Unused rail passes can be returned for a small fee.

I rarely book entertainment ahead of time, but policies would vary based on what was booked.

Good luck!

You will need to check with the individual companies - airlines, hotels, etc. - as they will each have a different policy. I'd be more comfortable booking one that offered complete refund in the event that they cancelled the flight, rather than a credit or voucher, as the latter two can often have conditions tied to them (e.g. must be used in one booking, booking must be of equal or greater value or unused credit will be forfeited, blackout dates, etc.).

Lots of hotels in Japan do offer free cancellation, even up to 1 day before your planned stay!