Adjusting the sense resistor value alters the charging current/ratio, which may or may not be possible depending on the power supply strenght/rating.
The maximum charge output voltage is generally shifted via “adjustment” of some sort of voltage divider in the circuitry. See here, for example: LiitoKala lii – 100 CHARGER Who Likes 'em? There are related mods for that charger there.
In general, output voltage adjustment is not quick and easy endeavour. As a DIYelver in my opinion it is probably best to buy inexpensive CC/CV modules and add them to an existing charger or DIY one with some inexpensive slot set. For example: https://www.aliexpress.com/item/5A-DC-To-DC-CC-CV-Lithium-Battery-Step-Down-Module-Charging-Board-LED-Power-Converter/32799532951.html
Cheers 