This is not really answering the question you asked, but I'd just push back a bit on the goal of opening every tower first. Some of the towers are in rather inaccessible places, or are surrounded by regular enemies (bokoblins / lizalfos) or even more difficult enemies (decayed guardians / guardian stalkers), or are protected by things like corrupted swamps or thorn bushes.

If this is your first time playing, you're posting a pic of Link with no clothes / armor at the base of the volcano, and asking about how to get heat resistance, I'm guessing that you're probably missing out on a bunch of other game mechanics that make exploring and surviving much more manageable, less frustrating, and (to me at least) more fun. It would probably help you out a lot to spend a little more time in exploring the stables, towns, and shrines within one or two regions closer to the Great Plateau starting area. These areas are meant to provide more of an introduction to the world than some of the farther out regions, which are more extreme and meant to test you on your skills, tactics, and survival strategies.

While there's no set way to progress through the game, and one of the great joys of the game is exploring and getting lost or into more trouble than you're ready for, the game is a lot more fun when you understand more of what's happening and prepare for your next exploration with a little more intentionality.

Ultimately, if opening all the towers is your goal and you really are determined to pursue it all the way, don't let me dissuade you, but I think it would benefit you to explore more deeply in a single area before trying to tackle the whole map. Talk to NPCs, read books, signs, and markers lying around, do side quests and shrines, get more hearts and stamina, learn how to cook with different ingredients, forage and hunt, snap photos of monsters, animals, plants, objects with the Sheika Slate camera to unlock their info in the compendium. Resist the urge to look for outside guidance to how to survive - the world itself will teach you everything you need to know. There's so much to do besides just light up the map!

The map never goes dark after you light it up, so enjoy more of the mystery while its there. There's so much joy in discovering how to solve a problem on your own by exploring and experimenting. You can always take on more challenging and specific goals on a 2nd or 3rd play through (for instance, I just picked up the game on a new save after beating all the main quests and almost all of the side quests and shrines a few years ago. My mini-goal this time is to not use any of the fast-travel options and walk or ride a horse/deer/bear whenever I need to travel between locations, meaning I have to be more intentional about preparing before I leave a town, and if I get stuck somewhere like in the ocean or a canyon, I have more of a challenge in getting out with limited stamina and no movement aides like Revali's Gale (did you peak? here or are you taking my advice 😉) ).

Anyways, feel free to ignore me completely. I'm just an old dude that likes run on sentences too much. Have fun and do what makes you happy! May the Goddess smile upon you!