The necessary tools;
- Metric open/box end wrenches
- Metric Allen keys
- Flat bladed and Philips head screwdrivers (I heartily endorse JIS #2 “Philips” head but regular type will work, mostly).
- Cone wrenches *
- Crescent wrenches. (Yes peanut gallery, I’m not really a fan but sometimes they come in handy. Headset top nut for example.)
- Penetraing oil
- Waterproof marine grease
- Pedal wrench is very handy *
- Square taper crank extractor *
- Cable cutters *
- Evaporust
- Chain breaker *
- Tape measure with mm markings
​​​​​​- Digital calipers for measuring

I think ^^ will handle ~90% of most repairs and many of the tools aren’t bike specific so will be useful for other stuff. (* tools are bike specific)

Round 2 of tools starts to get specific to your needs. For example, if you don’t have any freewheel or cottered crank bikes no need for those tools.

A lot of negative comments about Park Tool here but their stuff is easily available, reasonably priced, decent quality and has worked for me.

My 2 cents