Welcome,
Make your first flights low and slow in wide open spaces.
In fact make all your outdoor practise flight in such places.
If possible either print the manual or take an electronic copy with you and when you encounter behaviour you can not understand, read up on the relevant section of the manual. It is easier to understand in association with experience than it is to understand it in the abstract.
The RTH behaviours are one thing that can catch people out and should be experienced in safe practise before they are encountered for real.
If you get caught in wind, try to descend and do not rely on RTH to get you home. It gives you a directional heading but then switch to S mode to manually fight the wind. Remember the MM's ability to fight wind is limited compared to other models.
DO NOT set the RTH height ridiculously high, 10m greater than that needed to clear obstacles in the return flight path is probably sufficient. Go too high and you run the unnecessary risk of encountering high winds. Besides which excessive heights wastes power in bothe the ascent and descent.
Just for clarity are you sure it is the DJI Mavic Mini you have been given rather than a
DJI Mini 2? The former has a black controller and the latter a 'big' grey controller.
If it is the mini read up, here, on deformed propellor blades and the consequences.