Building on the earlier suggestion, you might want to consider going the used route with an adapter because older EF lenses are still incredible on the new R bodies. Specifically, I would suggest looking into the Canon EF 70-300mm f/4-5.6 IS II USM. I'd pick this over older zooms because it uses Nano USM technology, which is super fast for tracking fast-moving kids on a soccer field. Be careful though... you will definitely need the Canon Mount Adapter EF-EOS R to make it work on your R5. I always warn people to make sure they get a genuine adapter rather than a cheap knockoff, as the off-brand ones can sometimes feel wobbly or even lose connection mid-shot, which is the last thing you want during a big play. The 70-300mm is great for daylight, but since it has a variable aperture, just be aware that it might struggle if the game goes late or the weather gets really cloudy. Its basically the safest bet for your wallet right now without sacrificing too much quality. TL;DR: Grab a used Canon EF 70-300mm f/4-5.6 IS II USM and a Canon Mount Adapter EF-EOS R. Its a very reliable, budget-friendly combo that handles sports surprisingly well thanks to the fast autofocus motor. Just keep it dry since it isnt weather-sealed!

dont sweat it, i was in the same boat and honestly the Canon RF 100-400mm f/5.6-8 IS USM is exactly what you need. it works well in daylight and wont break the bank. ive been super happy with how it performs for outdoor sports like soccer. just make sure you have plenty of sun since its a slower lens, but for the price its been totally reliable.

This is exactly what I needed to hear. Youre a lifesaver honestly.