Over my 35+ years of desert touring, I've found it difficult to carry "enough" sunscreen to keep up with effective application guidelines, especially over extended periods of 3-4 weeks at a time. Some sunscreen lotions don't agree with me and my clothing over time, as I can taste it after application and it attacks the elastane elements in stretch clothing.
I've found my solution in sun-protective clothing -- Jerseys, shorts, sun sleeves for arms and legs, and a good "buff" to protect my scalp from sun through the helmet vents and my nose and neck from direct sun exposure.
I wish such things had been available in my earlier years of heavy sun and UV exposure, as I am paying the price now. I have completed repeated rounds of topical chemotherapy for actinic keratosis (pre-skin cancer) and for early-stage squamous-cell cancer and it isn't fun. Sunburn prevention really is key and your future self will thank you for taking precautions now.
My early jerseys and such were sourced from Brazil but as more people become aware, similar breathable/protective clothing that is sport-specific has become readily available as the market need expands. A lot of growth occurred in the construction and roofing fields, where need for all-day protection is great.
Here's some relevant links to helpful products...
https://www.buff.com/safety/hazards/sun/https://dabrim.com/products/cycling-classichttps://www.roadbikerider.com/top-cycling-apparel-uv-protection/https://www.pearlizumi.com/collections/sun-protectionI've found such products can command premium prices when purchased from "name" makers. Similar or identical products can often be found on eBay or Amazon, often produced in the same factories or as convincing, functional knockoffs for a fraction of the price. Tip: If you prefer a full-length jersey zip, leave it open only in the mornings and evenings when UV load is least. Otherwise, reflected rays from the road can really burn your chest, even when cycling on the drops.
Best, Dan.