My personal long-term experience shows that phone batteries need to be charged with a current of no more than 0.4-0.5A, then the capacity (after charging) and the number of cycles will be maximum.
Second - never buy smartphones in which, during even an average load (normal intensive surfing, etc.), it heats up above 36-37C. You will definitely have problems.
Third and key - the main problem with all smartphones (and other mobile gadgets, BUT not laptops) is that without exception, all smartphone manufacturers INTENTIONALLY use the worst form of smartphone recharging when the battery is fully charged and starts discharging, including self-discharge, when the smartphone is connected to charging. Unlike laptops, where recharging never starts before 95% of the charge threshold, and most often there is now direct control of thresholds (minimum and maximum) in many models, in smartphones, even a 0.3% charge drop automatically leads to recharging, which is natural and guaranteed kills any battery many times faster. This is an intentional CONSPIRACY of all smartphone manufacturers, because the charging start thresholds in reality can be programmed in the phone's firmware by issuing such commands to the charge controller, but this is not done intentionally so that you would rather come for a new smartphone or battery - and the latter (original, i.e. quality and with a guarantee) are most often not available in retail under the pretext that this service operation is no longer available to the consumer, which is also done intentionally in order not to sell spare batteries at retail and thereby make the average consumer dependent on the expensive prices of service centers or more often just force a replacement for a new smartphone model.
There are some alternative firmware that allow you to set the thresholds yourself, but there are few of them and, alas, they are generally buggy, because enthusiasts write them most often for themselves, without caring about testing all the functions.
The only way to clean up this mess and force manufacturers to make smart chargers like laptops that don't charge the battery until a certain threshold is reached is to make it legal. About the same as EU legislators forced Apple to switch to usb-c.
Only the active political and civil position of millions of smartphone users in the EU and the US will force all manufacturers, without exception, to make charging thresholds programmable.
With this kind of charging, you do NOT have to worry about turning off charging as soon as possible after reaching a full charge - the smartphone simply will not allow you to charge the battery until the charge drops to 95% (as in laptops) or to the threshold you set (for example, 85%). And thanks to this, you can easily keep your smartphone on charge at home for days on end without worrying about recharge cycles at all - you will always have the maximum performance of your smartphone and it will be at least 95% charged, without deliberately killing the battery by collusion of manufacturers.