Most of the time many components can be identified easily.What you need to know is what package is used. Exact dimensions and footprint are crucial. Larger packages may have a manufacturer logo that can narrow down the search. Model numbers will be the first to appear after logo most of the time.
There are resources that will help.
https://smd.yooneed.one/ https://www.s-manuals.com/smd https://www.sos.sk/pdf/SMD_Catalog.pdfThere are others.
Where the component used in a circuit is very important. Other components it's connected to, in circuit, can help identify it purpose. Circuit diagrams of the device help a lot if available. Drawing out a picture of the copper traces to each pin and any components connected to those traces. Photos of both the Front and Back of the circuit board.
#1 Has an ALPHA and OMEGA logo with the model number 66644 beside it. The package is a Dual-Flat No-leads 8 (DFN8). Just from that I can search and find AONS66644 which is a 60V MOSFET.
#2 is a SOD-123 diode marked SL. 1N5819 1.0A Schottky barrier rectifier
#3 SOT23 Marked A7 BAV99 High-speed switching diodes
#4 SOT-23-3L 3415 Huamei Semiconductor Linear voltage regulator IC LDO, 1.5V±1.5%, 500mA
#5 SOT-23-5 or SOT-25 This is where a circuit diagram comes in handy as it could be a Linear voltage regulator or Voltage detector
#6 SOT-23 2SC4410 NPN transistor
Now this does not guarantee perfect success, but having as much information as possible about the component helps.