No for several reasons.
First, theres a soft MMR reset at the start of season, so whatever your MMR is now, it'll be different when you do your placements.
Second, OP.GG and other sites only estimate your MMR, and sometimes it's almost certainly wrong if you look at LP gains/losses sometimes.
Third, ranked MMR and normals MMR are separate, so even if you were playing with challengers in normals, you'd still have a starting ranked mmr if you've never played ranked before. That starting MMR is roughly silver 4ish.
Fourth, the outcome of your 10 placement matches is a pretty big influence on where you end up. If you go 10-0 as a first time ranked player it's possible to get placed high gold or even plat 5 (if you happened to get 'lucky' in your placements to get matched against relatively high mmr people compared to your own each time e.g. due to premades), meanwhile if you end up 0-10 you'd likely be in the bottom half of bronze.
Broadly speaking almost everyone ends up high bronze or low silver when they first start ranked though, so I'd adjust your expectations accordingly.