LarrySellerz not everyone has the same motor, some of us don’t need the low-low gears to up hills, and some of us spin out 50x11. BEar that in mind before you offer
advice opinions about gearing based on your abilities. I admittedly struggle with this when people ask how to build a Franken-geared bike with sub-20 gear inches on the low end.
Capacity is NOT the largest cog your derailleur was designed to accommodate (which for Shimano is ALWAYS conservatively spec’d).
Addressing the largest cog issue first, turning the b-screw will often allow use of a slightly larger cog, just how much larger is not universal from RD to RD, so you really need to do some research and/or experimentation. One word of caution, a tooth or two larger is usually not an issue, but 3 or more than lead to shift issues, first smoothness and potentially also skipped or missed cogs especially as you get into the higher end (smaller cogs) of the cassette.
Capacity is a function of how much chain the derailleur can wrap (rear), or how large of a gap between chainrings it can manage (front). The wrap on the rear is a combination of tooth difference from large to small on the cassette and the difference between large and small chainring. So, going to a 53 and 34 (from a 50 and 30 respectively) should be no issue, though you may need a slightly longer chain.